The A's have dominated the first two games of the series, winning 8-0 and 12-3 to run their winning streak against the Rangers to seven. Oakland has already clinched the season series with a 13-5 advantage.
The A's (94-61) have won four straight and 10 of 11 overall, a hot streak that's allowed them to catch and pass both Tampa Bay (92-63) and Cleveland (91-64) in the three-team tussle for the American League's two wild-card playoff spots.
The team with the best record of the three at regular season's end next Sunday will host the single-elimination AL Wild Card Game.
Roark (10-8, 4.12 ERA) almost surely would not be a candidate to pitch that game for the A's, but he remains in the running to be in the rotation should Oakland advance to the best-of-five AL Divisional Series.
The Wild Card Game winner is assured of opening the ALDS on the road, meaning its third and, if necessary, fourth starters would be in line for home games.
That's where Roark would command consideration, as he's gone 3-0 in five home starts for the A's since being acquired in a trade from Cincinnati. Two of the 32-year-old's wins have come against current division leaders St. Louis and the New York Yankees.
As well as Roark has pitched, cracking the A's top four come playoff time could be tough. Mike Fiers and Sean Manaea are basically sure-things, while Brett Anderson and Homer Bailey, like Roark, are experienced guys who are strong candidates.
Fiers noted the in-house competition after pitching a gem in the series opener on Friday.
"Everyone else in the rotation is throwing well, so coming out today I needed to make a statement," he told reporters after the game. "Everyone wants to make it tough on (manager) Bob (Melvin) to choose what plan they want to go with."
Remaining unbeaten in Oakland will be no easy feat for Roark, who has never beaten the Rangers in three career starts, going 0-3 despite a 2.25 ERA. He allowed all four runs in seven innings in a 4-3 loss to Texas for the Cincinnati Reds in June.
Lynn (14-11, 3.77), meanwhile, has personal milestones to pursue in his final road start of the season.
The 32-year-old begins the day seventh in the AL in strikeouts with a career-high 224, but with a chance to move into the top four. He has never finished higher than ninth in his league.
He's also seeking to go over 200 innings (he needs 4 1/3) for the first time since 2014, which is also the last time he won 15 games.
"When you show up at spring training, (the goal) is 200 innings and strikeouts," Lynn told reporters earlier this week. "That's grown-man stuff. That's what it means. It's been a few years for me since I've (gotten to 200 innings)."
Lynn won at Oakland in July, allowing just one earned run in six innings in a 5-2 win. It raised his career record against the A's to 1-1 with a 6.46 ERA in three starts.
He hasn't won since Aug. 2, however, a stretch of eight starts during which he's gone 0-5.
--Field Level Media