Scott Dixon has tightened his grip on the Verizon IndyCar Series after a restart mistake from Josef Newgarden ultimately handed the New Zealander victory in Toronto.

The pivotal moment came upon the first restart on Lap 34 when Newgarden, as leader, skated up to the wall on dirty track before the field had even made the control line.

Each of the other three title contenders also struck during the 85-lap race around the streets of Exhibition Place, including multiple problems for Will Power and Alexander Rossi during a chaotic first half of the race.

Pole-sitter Newgarden led the field through the opening corners from Dixon, Ryan Hunter-Reay, Power, Rossi, and Pagenaud, the latter of whom had been kept wide at Turn 1 due to a big dive from Power.

Takuma Sato quickly gained two positions to run fifth and he was the main mover by the time the front-runners reacted to Sebastien Bourdais’s slide into the wall and pitted on Laps 23 to 24.

Power jumped Hunter-Reay through the stops to sit effectively third before Hunter-Reay ran into the wall on Lap 28, prompting a Caution.

In an unrelated incident, his Andretti Autosport team-mate Alexander Rossi broke the front wing on the #27 Chevrolet when he rear-ended Power.

It was then that it became apparent that the Australian’s #12 Team Penske Chevrolet had a damaged right-rear toe link, likely a cause rather than symptom of the contact.

He pitted under the Caution, as did the wounded Andretti pair for new front wings, before the race-changing restart.

Not only did Newgarden glance the wall in the #1 Team Penske Chevrolet, dropping to fifth before he too had to pit to check the toe link, there was carnage at Turn 1.

Graham Rahal (#15 Rahal Letterman Lanigan Honda) locked up and spun Max Chilton (#59 Carlin Chevrolet), with Power, Sebastien Bourdais (#18 DCR w/ Vasser-Sullivan Honda), and Hunter-Reay caught in the incident.

So too was Rossi, who launched off Hunter-Reay’s #28 Honda as he tried to drive through and had to return to the pits for a third front wing.

Robert Wickens had been lurking in the back half of the top 10 but a great restart had elevated the #6 Schmidt Peterson Honda to second position, behind Dixon.

Marco Andretti (#98 Andretti-Herta w/ Curb-Agajanian Honda) had been rising through the field and he passed Sato for fourth after a couple of attempts in the next short run of green flag racing.

That came to an end on Lap 42 due to Rene Binder and the stalled #32 Juncos Racing Chevrolet at Turn 8.

A third and final restart came on Lap 45, when Pagenaud had to defend his position from Marco Andretti.

The race finally settled down as Dixon and the #9 Chip Ganassi Honda skipped three seconds clear of Wickens.

The final pit stops cycle took place with around 30 laps remaining and Dixon held onto the effective lead despite trouble changing the right-front.

Pagenaud, however, got back onto the track in front of Wickens and the Canadian, brakes locked, nudged the #22 Team Penske Chevrolet through Turn 1.

He went to the outside of the Frenchman at Turn 3 only for Pagenaud to feed him towards the wall and keep the spot, but race control decided the manoeuvre was fair.

Dixon had been as many as eight seconds clear but that margin dropped to less than three seconds as the effective leader got stuck waiting for Hunter-Reay, who was trying to stay on the lead lap, to make his final pit stop.

The Kiwi even brushed the wall but, once released, was comfortable until the end and now leads Newgarden by 62 series points with five races remaining.

Pagenaud took the chequered flag over five seconds adrift, ahead of Canadians Wickens and James Hinchcliffe (#5 Schmidt Peterson Honda).

Charlie Kimball (#23 Carlin Chevrolet), Tony Kanaan (#14 AJ Foyt Racing Chevrolet), and Zach Veach (#26 Andretti Autosport Honda) filled fifth through seventh.

Rossi and Newgarden managed to finish on the lead lap in eighth and ninth respectively, while Marco Andretti dropped from fourth to 10th when he had to pit for fuel with a lap remaining.

Hunter-Reay and Power were both running at finish in 16th and 18th, but Sato (#30 Rahal Letterman Lanigan Honda) was a DNF in 22nd after he hit the wall in the final 20 laps.

Race 13 is the Honda Indy 200 at Mid-Ohio on July 27-29 (local time).

Race results: Toronto

(C)hassis: D=Dallara | (E)ngine: C=Chevy, H=Honda | (T)yre: F=Firestone

Series points