Nearly two months ago, they entered Turn 4 on the streets of St. Petersburg battling for the race lead and both wound up in a tire barrier.

Romain Grosjean vs. Scott McLaughlin Part 2 – followed shortly by Part 3 – on Sunday at Barber Motorsports Park was better. McLaughlin got the last laugh after the pair swapped the lead multiple times in the final stint to pick up his fourth IndyCar win, and first this year.

Here’s how he did it.

Pivotal strategy calls at Barber

As is always the case with the 90-lap affair on the 2.3-mile natural terrain road course just outside Birmingham, Ala., strategy played a major role. Teams decide between taking just two pit stops – and having to fuel save throughout the race – or three – and giving up roughly 27 seconds on pitlane but being able to push full-bore throughout the race.

Team Penske went all-in on the three-stop strategy, putting McLaughlin, Will Power and Josef Newgarden on black tires to start the race with the bulk of the front pack starting on red tires and planning to take two stops.

Notable drivers on the two-stop plan Sunday included Grosjean, Pato O’Ward, Alex Palou, Christian Lundgaard, Scott Dixon, Kyle Kirkwood and Marcus Ericsson. Those on the three-stop strategy included McLaughlin, Power, Newgarden, Alexander Rossi and Felix Rosenqvist.

Mid-race caution sets up battle for the lead

The race stayed green through the first third of the race, allowing drivers on both plans to make their first stops comfortably. Dale Coyne Racing’s Sting Ray Robb slowed off-course in Turn 9 on Lap 38. As they’ve recently done when stopped cars have been off-track and off-line, race control let every car make one opportunity to make a pitstop before throwing the caution.

More: IndyCar race incidents at Barber Motorsports Park in Alabama

Newgarden had already made his second stop, and Rossi, McLaughlin, Power and Rosenqvist, among others made the move moments before the caution was called. With the two-stoppers just 10 laps or so into their middle stint with 20 left before pitting, the caution bunched up the field with everyone needing just one more stop. The two-stoppers, including race leader Grosjean, were forced to save fuel the rest of the way in the wake of a short three-lap caution.

Grosjean, McLaughlin trade lead

Somewhat unexpectedly, Grosjean held off McLaughlin in 2^nd-place through that middle stint, even managing to increase his lead by almost a full second over seven laps. By Lap 56, Grosjean's lead was back down to 0.6 seconds, but just before he pitted on Lap 61, the Andretti Autosport driver boosted his edge to 2.6 seconds.

The in-laps, out-laps and pitstop times appeared they may make the difference. McLaughlin, who made his final stop on Lap 64, blended back into the lead with both drivers finishing the race on the same Firestone primary tires. Grosjean, by virtue of having already warm tires, managed to grab the lead by the end of the lap. Similarly to St. Pete, Grosjean bounced outside of McLaughlin in the lead entering a left-hand turn in Turn 16, and the pair made it through. The Andretti driver held the inside into Turn 17 and took off into the lead. Within three laps, Grosjean had a 1-second lead on the charging Team Penske driver, but then McLaughlin really showed his cards.

McLaughlin, Power snag two podium spots for Penske

On Lap 72, Grosjean slipped outside entering the hairpin Turn 5-6 complex, allowing McLaughlin the chance to pounce. Again wheel-to-wheel, McLaughlin took back the lead and cruised ahead, building a 1.7-second lead by Lap 75. By then, Grosjean had used all his push-to-pass boost and had to save fuel, while McLaughlin still had more than 30 seconds of push-to-pass left.

“I call that the ‘happy driver’ strategy. I was a lot happier doing that,” McLaughlin said post-race. “We just raced hard. That was (three races) ago, and we just got on with it. We’d talked man-to-man, and as far as I’m concerned, we raced hard and fair.

“It’s been coming. We’ve been close but hadn’t quite had it in the last couple rounds.”

In the closing laps, Grosjean had to keep an eye on Will Power, who started 11^th but finished with one of the shortest stints in the field and was closing fast on alternate tires. The defending series champ was 10.6 seconds back from the lead with 20 laps to go but by the final lap had pulled within 1 second of Grosjean. However, the Andretti driver held onto his fifth career runner-up in IndyCar and second in a row.

“This hurts,” Grosjean said of another 2^nd-place finish. “The three-stop never wins at Barber, but today it did. The pits stayed open on that yellow, and it gave Scotty and Will a chance to go three. I just got unlucky with that yellow, but (team co-owner and his strategist) said ‘Don’t have your head down. That was one of the best drivers I’ve ever seen.’

“I gave it all, but congrats to Scott. He deserved the win.”

This article originally appeared on Indianapolis Star: IndyCar: Scott McLaughlin holds off Romain Grosjean for Barber win