Luca Filippi's day also ended early on lap 13 with the back of the #98 Barracuda Racing/Bryan Herta Autosport car catching fire in turn 3 while the race was already under yellow when Ed Carpenter made what he himself described "a dumb mistake" which saw him lock up and slide into the tyres at turn 5.
"I felt the car stop, I lost the drive," said Filippi. "It's a shame because the Barracuda Racing car was very fast during the weekend and especially in the race. I felt that I was following the guys at the top and I actually think I was faster."
Racing resumed on lap 19, with Pagenaud passing Dixon for second in turn 1 and Charlie Kimball and Graham Rahal moving up to fifth and sixth. Wilson had opted to join the group of cars to pit under the caution putting him down in 13th with all but one of the cars ahead yet to make their first stops; unfortunately a lock up sent the #19 Dale Coyne Racing car down a run-off and Wilson plummeted to 19th spot by the time he was able to rejoin.
A close encounter with the wall saw Newgarden haemorrhage multiple positions and drop to eighth spot moments later before his own first visit to pit lane of the afternoon on lap 25. The leaders weren't in for another four laps however: Pagenaud in first, Kimball and Rahal in on lap 30, Dixon stretching it another lap further and Power not coming in until the end of lap 32 having built up a seven second lead. A slow stop for the #12 as a result of running over an airhose and ending up being out of position too close to the wall saw the time margin at the front that Power had previously built up promptly evaporate; when it rejoined, the Penske car came under all types of pressure from a determined Dixon over the next few laps, but ultimately to no avail despite a furious Dixon's accusations of blocking.
Opting for an earlier stop now left Sebastien Bourdais in charge of the race ahead of Vautier, Sebastian Saavedra and Helio Castroneves. Bourais came in for his second stop on lap 40 just before the second full course caution of the day for Stefan Wilson who had put the second Dale Coyne Racing car into the wall at turn 7. A flurry of pit stops in response to the yellow enabled Bourdais to reclaim the top spot ahead of Power and Dixon with Saavedra slotting into the gap left by a slow EJ Viso in fifth place, the #5 holding up a pack of cars that included Graham Rahal, Oriol Servia and James Hinchcliffe.
The caution was extended by Ryan Hunter-Reay abruptly coming to a halt in turn 10: "Out of nowhere the car just died," he recalled. "Electronics cut out on it, battery voltage looked good and then all of a sudden it just fell through the bottom. It's heartbreaking."
When the race resumed on lap 47 Bourdais maintained the lead into turn 1 but behind him Dixon was tipped into a spin by Graham Rahal that led to the entire track being blocked by the rest of the field piling into the corner behind them. Once everyone was restarted and sent on their way, race control sorted out the correct running order and cars made opportunistic visits to pit road leaving Bourdais still in the lead ahead of Rahal, Power and Servia with Dixon only dropping to fifth as a result of the incident ahead of Kimball, Viso and Saavedra.
At the restart on lap 53, the race didn't even make it down to turn 1 before there was a dramatic collision: Scott Dixon had got a huge run down the inside of Power as they passed the line, when the #12 suddenly jinked hard to the right, seemingly to make his own pass on Bourdais ahead rather than to ward off Dixon's move behind. The two made heavy impact, Dixon thrown into the wall and damage also done to Power's right rear suspension in a collision that will do nothing to soothe the skyrocketing tensions between the Penske and Ganassi camps on pit road after the controversial incidents last week at Sonoma.
"On the restart I had an overtake advantage on Power," said Dixon. "It must have been in fourth-gear, so they can't complain about wheel spin. Then I got beside him and he ran me straight into the wall."
"I feel really bad," said a chastened Power after seeing the replays. "I thought I had a really good run on Bourdais and I was going to the inside to get around him and I thought I hit a bump or just lost it on cold tyres. I really had no idea that Dixon was there. I actually didn't even know until I got back to the pits and they told me. I feel terrible for him and his team. All I can do is tell them how sorry I am and move on to Houston."