Ericsson, who had been leading by three seconds before the red flag came out for Jimmie Johnson’s shunt, employed a series of weaving defensive manoeuvres down the straight over the final two lap shootout to stave off the Arrow McLaren SP driver’s attack over the penultimate lap.
But on the exit of Turn 4 O'Ward had greater momentum and, when Ericsson protected the inside, the Mexican driver flicked right to draw alongside on the outside into Turn 1.
But Chip Ganassi Racing driver Ericsson had eased right in order to get a good line through the turn and was not about to capitulate, so O’Ward had to back off.
“He was going to put me in the wall if I would have gone for it,” O’Ward told NBC. “We were alongside each other.
“I’m so proud of the team and proud of myself. We did everything to get it done, and even getting a massive run on him. We had no wicker, less downforce and still not enough speed to get by him, even with a massive run.
“It’s frustrating; it’s bittersweet. I’m so proud but it definitely stings because I feel like the team and I did everything perfectly to get it done, and something that was out of our control was why we struggled in the end.
“All these guys deserve it, and I felt like I drove a race to position us there. It’s just a bummer – a bummer we didn’t have more.
“We have work to do, and we’ll come back next year, and we’ll come back faster, with a better race car and go at it again.”
O’Ward’s team-mate Felix Rosenqvist finished fourth after a strong Month of May for the Arrow McLaren SP team, and in contrast with O’Ward was upbeat.
The Swede had taken the advantage in the final pitstop cycle, emerging ahead of O'Ward and Ericsson, but was soon swallowed by the pair and also lost third to Ganassi's Tony Kanaan.
“It feels good man, I’m so happy with our Arrow McLaren SP Vuse team,” he said.
“I feel like we just had confidence through these last few weeks. We’ve been strong all year, we’ve had good speed, and I think today we had probably had the best pitstops out of anyone.
"On one pit sequence we came in eighth and came out fourth and that’s the kind of confidence we need, that’s what we need for the rest of the season. I’m really proud of them.
“Obviously when you lead a race you want to win it, and then you want to get a top three if you can’t win it. I had a good battle with Tony on the last lap, side-by-side through the first two corners, and it was super-tight, man. But good for him.
“Also good for Marcus winning his first 500. I know how much that means to him and that’s a huge achievement for his career. Really cool to see the Swedish flag up there.”
Following the restart, Rosenqvist got a strong tow from O’Ward down to Turn 1 and seemed like he might make the pass down the inside.
“I thought, ‘I could come out of this in first or maybe last!’” he said. “Everyone went for it for a two-lap shootout, so honestly I’m just happy I made it through, because it was tight.”
