HOUSTON -- After earning at worst a series split with a 3-1 victory Wednesday night, the Toronto Blue Jays enter the series finale against the Houston Astros almost as concerned with the start they'll get the following day.

Left-hander J.A. Happ (14-3, 3.16 ERA) starts the series finale for the Blue Jays (61-47). Happ is 3-1 with a 3.50 ERA in six starts against the Astros, for whom he went 18-28 with a 4.84 ERA over parts of three seasons following his trade from the Phillies on July 29, 2010.

Left-hander Francisco Liriano (6-11, 5.46 ERA) follows Happ in the rotation, making his first start with the Blue Jays on Friday night in Kansas City against the Royals. Liriano and two prospects joined the organization Monday following a trade deadline deal with the Pirates.

Liriano has scuffled this season as he led the majors with 69 walks prior to the trade. But the Blue Jays are confident that Liriano can be reborn, in part because he will be reunited with former Pirates catcher Russell Martin.

"I think you just need to watch him and let him go out and pitch before you jump the gun," Blue Jays manager John Gibbons said. "He's back with Russ. Let him pitch. There's nothing worse than trying to pinpoint something in someone's mind before you see him.

"He may go out there and shine like there's nothing to it."

Right-hander Mike Fiers (7-4, 4.42 ERA) starts the series finale for the Astros. Fiers has appeared in just two games (one start) against the Blue Jays in his career, going 1-0 with a 1.13 ERA over eight innings. Once in the precarious position of losing his spot in the rotation, Fiers has rebounded to go 1-0 with a 2.03 ERA over his last two starts.

Like the Blue Jays, the Astros (56-51) have one eye on their weekend rotation. With right-hander Lance McCullers landing on the 15-day disabled list with a mild elbow sprain, rookie right-hander Joe Musgrove makes his first career start against the Rangers on Sunday.

Musgrove excelled in his major league debut on Tuesday night, pitching 4 1/3 scoreless innings of relief with eight strikeouts, matching the major league record for strikeouts in relief in a major league debut. Musgrove arrived from Triple-A Fresno on Sunday poised to start in place of right-hander Doug Fister (paternity list) on Monday night.

Instead, opportunity knocked one day later and Musgrove validated the trust the organization showed with his promotion.

"We thought he could handle it which is why we were going to give him an opportunity if Fister was gone," Astros manager A.J. Hinch said. "We really like this guy. He's got a lot of charisma; he's got a lot of polish to him. Even to be able to come in and warm up in front of a full crowd and both teams waiting and the umpire sort of pushing the action, it's not easy. His maturity came through with rave reviews.

"He made some really good hitters look uncomfortable and I think that's a good sign. He's going to have a big test with his first start against the Rangers but I think the way he's handled this season, the way he's matured over the year is why we gave him the opportunity on the front end."

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