The lefty worked his second straight and third of the season, dealing a career-high 132 pitches as the Sooners knocked off Kansas 4-1 in Friday's series opener at Hoglund Ballpark in Lawrence, Kan.
John struck out eight and walked none, surrendering just an earned run in the contest.
Meanwhile, the bats provided plenty of offense for him.
In fact, the Sooners took a 2-0 lead before he ever took the hill, plating a pair of runs in the top of the first.
Left fielder Erik Ross, who led off the game with a walk, scored later in the inning on a passed ball, and center fielder Max White knocked home second baseman Jack Mayfield, who followed up Ross' base on balls with a single.
A one hour, 39-minute rain delay then ensued after the third inning.
But John and the Sooners came back with the same energy they had before the break in action.
OU added two more runs in the sixth when White singled home Mayfield, and right fielder Cody Reine followed up with an RBI double down the right field line scoring White.
John allowed his lone run in the bottom of the seventh on an RBI triple by Kansas third baseman Zach Elgie.
The victory raised OU's overall record to 27-16 and pulled them even in Big 12 play at 8-8 after losing eight of its first 12.
OU has won nine straight games in the series, and game two in this three-game set is slated for 6 p.m. Saturday.