NORMAN – Aaron Baker has a thing for postseason baseball. With one big swing Sunday, Baker kept Oklahoma’s postseason going, his grand slam stamping a 7-2 win over Washington State in the Norman Regional at Mitchell Park. That’s one elimination game down, two to go for the Sooners, who still face a rugged road to the tournament title. They advance to face Arkansas at 7 p.m. Sunday, hoping to force an if-necessary game with the Razorbacks Monday night. The Hogs dropped OU into the loser’s bracket with a 17-6 rout Saturday night. For Baker, it was his fifth postseason home run in seven NCAA games. “He’s always terrific, it seems, in postseason,” said Sooners coach Sunny Golloway. “He always steps up to the great challenge. And I thought our whole club did.” Before an afternoon crowd of 1,439, Baker broke open a tight game with a seventh-inning blast. “It was a fastball, but really I was just trying to square a ball up and drive in a run,” Baker said. OU had just taken a 3-2 lead on J.T. Wise’s bases-loaded, infield single. With the left-handed hitting Baker coming to the plate, the Cougars brought in left-hander Adam Conley from the bullpen. Baker ripped Conley’s first pitch – and only pitch – far over the wall in right. “I think you can always hit a ball further,” Baker said. “What matters is I was able to drive some runs in, whether it was one or four, I’m just trying to do my job.” Garrett Richards gave the Sooners a complete game pitching performance, striking out 10 and allowing five hits. Richards, who improved to 9-4, threw a career-high 136 pitches and also set a career-best with the nine innings pitched. After allowing a two-run home run in the second, Richards allowed just three hits the rest of the way and didn’t allow a runner past second base. “The way he pitched with a 2-2 tie is the key to me,” Golloway said. The Sooners will send right-hander Stephen Porlier to the mound against Arkansas tonight.