Sebastien Buemi held off di Grassi to win the 2017 Monaco ePrix

Sebastien Buemi won the 2017 Monaco ePrix from pole, holding off Lucas di Grassi over the final laps and taking his fourth win of the season. The race was a 51-lap contest around the Circuit de Monaco, and it was held on 13 May 2017.

Why did Monaco return to the Formula E calendar?

Monaco returned after a year away, filling the slot the Historic Grand Prix occupies every other year. A local law limits the principality to two races a year, which is why the ePrix had to take that slot. It was the second Monaco ePrix, following the first in 2015.

The race had first been proposed after the Moscow ePrix was cancelled in the 2015-16 season, but the preparation time was too short. The FIA World Motor Sport Council confirmed the Monaco round as part of the 2016-17 schedule in September 2016, as the fifth of twelve single-seater races.

Elsewhere, the track was a 12-turn clockwise street circuit of 1.765 km (1.097 mi), the shortest on the 2016-17 calendar. It was heavily modified from the layout used for the Formula One Monaco Grand Prix.

Buemi took pole, managed his energy and kept di Grassi behind him to win Monaco for the second year running.

How did the championship look before Monaco?

Buemi led the Drivers' Championship with 76 points, six ahead of di Grassi in second and a further 25 ahead of Prost in third. Vergne was fourth on 46 points and Bird fifth on 33. Seven races remained after Monaco, so the title was still open.

In the Teams' Championship e.Dams-Renault led with 122 points, and Audi Sport ABT were second on 91. Virgin, Techeetah and Mahindra were contending for third.

Buemi had finished fourteenth at Mexico City and arrived in Monaco as the pre-race favourite. Di Grassi, who knew the track well as a Monaco resident, had won in Mexico City and wanted to carry that momentum into the principality.

Who was in the field at Monaco?

Twenty drivers from ten teams were entered, two per team. Jose Maria Lopez's place was in doubt after an earlier injury to his spine from a crash at Silverstone, until the FIA medical team cleared him after the first practice session.

Robin Frijns injured his right knee ligaments while training. Andretti had Alexander Sims ready as a replacement if Frijns had further problems, but Frijns raced. Virgin had Alex Lynn on standby in case Lopez could not continue.

Esteban Gutierrez received a new Techeetah chassis after a handling imbalance, which the team said was possibly caused by damage from his predecessor, Ma Qinghua, in earlier crashes. The team's request to change it was accepted by the stewards.

How did practice and qualifying set the grid?

Buemi set the fastest first-practice lap at 52.795 seconds, four-tenths ahead of his teammate Prost, and he was fastest again in the second session at 52.729 seconds. The rest of the top ten in that session were Bird, di Grassi, Vergne, Lopez, Duval, Abt, Piquet, Prost and Sarrazin. He had pole in qualifying with a lap of 53.313 seconds.

Turvey braked hard under yellow flags to avoid Buemi, and Rosenqvist ran into the back of his car, which ended first practice early. Prost spun at turn three, and Carroll stopped close to a barrier at the Anthony Noghes corner.

Qualifying was held in dry weather, and the first group ran on a slippery surface that improved as the session went on. Buemi was fastest in the first group on his maximum power lap, half a second quicker than Duval, with Mitch Evans third. Heidfeld was quickest in the second group, four-tenths of a second ahead of Gutierrez.

In qualifying Vergne set the fastest overall group lap of 53.286 seconds, while Engel and di Grassi had been among the quickest in the earlier groups. In Super Pole di Grassi slid into the wall and still qualified second, while Piquet took third and Vergne fourth.

Buemi's pole was his second in a row in Monaco and the seventh of his career. It was also his first since the 2016 London ePrix. Duval started at the back after going over the lap limit in qualifying.

How did the start unfold in Monaco?

Buemi kept his lead into Sainte Devote, with di Grassi right behind him. Bird made the best getaway in the field and gained three positions by the end of the first lap, while Sarrazin stalled after leaving the grid and dropped to the back.

On lap eight Bird went over the kerb at Tabac, lost the rear of his car and hit a barrier. He had to pit, and Lopez was shown a black flag with an orange circle and then stopped to repair his rear wing. Both drivers returned to battle for the fastest lap.

Vergne and Piquet collided at the Novelle Chicane, after both locked their tyres. Vergne was left in the barrier, and the safety car came out on the following lap so the cars could be cleared.

Why did the safety car change the race?

The safety car let every driver make the mandatory change into a second car under neutral conditions. Duval and d'Ambrosio were first into the pit lane, and the race restarted when the safety car came in on lap 26 with Buemi leading di Grassi and Heidfeld.

Buemi slowed to conserve electrical energy and used his FanBoost to hold the gap he had built over di Grassi. He was one second clear once the race resumed, and he kept his advantage as he managed the energy.

Di Grassi narrowed the gap to half a second with six laps remaining, but he could not use his own FanBoost because of battery voltage limits. He forced Buemi to defend at the Swimming Pool and La Rascasse, yet the run to the line was not long enough for a pass.

Who else scored and what went wrong?

Heidfeld finished third and became the first person to stand on the Monaco rostrum in both F1 and FE. He said Mahindra had discussed its strategy heavily and that following di Grassi had helped the team finish on the podium.

Felix da Costa was penalised 33 seconds for an unsafe release from his garage, which dropped him from ninth to eleventh. Frijns lost all his electrical energy on the final lap and fell from eighth to twelfth.

Vergne hurt his right hand in the collision with Piquet and needed an X-ray. He said he would be fit for the next race in Paris, but he believed the incident had destroyed his race. Piquet called him impatient and said it was a racing incident.

How did the standings change after Monaco?

Buemi extended his Drivers' Championship lead over di Grassi to 15 points. Prost stayed third on 48 points, Vergne was fourth on 40, and Bird's fastest lap cut his gap to Vergne to six points. Mahindra's rise from fifth to third was the most visible move in the teams' table.

e.Dams-Renault increased its Teams' Championship lead over Audi Sport ABT by six points, and Heidfeld's podium was a key part of Mahindra's climb to third. Mahindra moved from fifth to third. Techeetah overtook Virgin for fourth with seven races left in the season.

How did the teams read the safety car?

Buemi said his team had studied the tactic of making pit stops early, the approach Audi Sport ABT had used at the season-opening Hong Kong ePrix and at Mexico City. He felt it was the right decision, even though it made finishing harder, because he had to conserve electrical energy for the whole of the closing stint.

Di Grassi said his first stint lacked pace because he was saving energy. He had hoped to make up the ground in the second half and attack at the end with the right strategy. He did not want to risk a collision with Buemi, since there were few overtaking places in the tight Monaco streets.

What did Piquet and Vergne say about their crash?

Piquet said he was annoyed by Vergne's attempts to pass him at the Novelle Chicane. He thought Vergne had put himself in that position by refusing to be overtaken on the outside, and he called the contact a racing incident in which he had only been defending his place.

Vergne did not speak to Piquet after the race, because he believed the crash had cost him a podium. He later said he did not regret the move, which he saw as part of motor racing.

What makes the Monaco circuit different?

The Monaco circuit is short and tight, and its corners, from Sainte Devote to Tabac and La Rascasse, reward precise braking and a clean exit. Overtaking is rare, so energy management and the safety car mattered most. The track was heavily modified from the Formula One layout, which made it a distinct Formula E challenge.

Each lap is short, which leaves little room for error at Sainte Devote, Tabac or the Novelle Chicane. Drivers still had to find the balance between pace and electrical energy across the twelve corners.

Buemi called Monaco one of the best tracks on the calendar and said he had great memories of 2015. Heidfeld had extensive experience of the track from other motorsport series, and he said a competitive car gave him real hope of a result.

Di Grassi, who lives in Monaco, called it his home race and said his local knowledge of the track helped him prepare for the weekend.

What was the weather like for the Monaco race?

The race started in dry and sunny weather, with the air between 20.0 and 20.8 C (68.0 to 69.4 F) and the track between 24.4 and 25.6 C (75.9 to 78.1 F). A 10 per cent chance of rain had been forecast, and conditions were expected to stay consistent.

Separately, the race began at 16:00 Central European Summer Time before a crowd of 18,000 people. Monaco's narrow streets made the start tight, and the concertina effect at Sainte Devote caught some drivers out.

Piquet hit the barrier but avoided serious rear suspension damage, while Abt's own rear wing and nose cone were damaged when he ran into the back of Lopez. Bird made the equal best getaway in the field. The pack then settled down for the next six laps with nothing notable happening.

How did the stewards handle the Monaco incidents?

Gutierrez was investigated for an unsafe pit stop release, but the stewards chose not to penalise him, and he finished eighth on the road. The one penalty that changed the order was Felix da Costa's, which moved him back from ninth to eleventh.

Duval, who had started at the back after exceeding the permitted laps in qualifying, retired with regenerative braking problems. D'Ambrosio also retired, with a powertrain malfunction, and neither driver was in contention at the finish.

Monaco 2017 leading finishers