Taijuan Walker may be making his season debut, but Seattle's top prospect already knows Houston relatively well.
Walker will face the Astros for the third time in four major league starts Monday night as the Mariners open a three-game set in Houston after winning their last three series.
Seattle (44-38) took two of three from Cleveland over the weekend after winning sets with Boston and Kansas City. The Mariners are 10-4 with a 2.40 ERA since June 15 after Felix Hernandez and Fernando Rodney combined on a one-hitter in Sunday's 3-0 win over the Indians.
Manager Lloyd McClendon's team hasn't gained any ground on AL West-leading Oakland during the run of success, but it is positioning itself nicely as the wild-card situation begins shaping up in the final weeks before the All-Star break. He now gets to add the organization's most promising young arm to the mix.
"I've read and heard all the accolades. I saw a little bit of film, but I haven't seen him in competition," McClendon told MLB's official website. "Hopefully he goes out and gives us five or six good innings. We'll take it from there."
Walker was 3-1 with a 3.38 ERA and 46 strikeouts in 40 innings of eight starts in the minors before being recalled.
He made three starts last season, going 1-0 with a 3.60 ERA. The win came in his big league debut on Aug. 30 in Houston, and he faced the Astros again on Sept. 9 in his last start. The right-hander allowed two earned runs and seven hits while striking out 10 over 10 innings in those games.
Jose Altuve went 2 for 5 while the rest of the current Astros combined for a 3-for-23 mark against the 21-year-old.
The Altuve he'll face in this series is a bit more locked in. The second baseman collected three hits with two stolen bases in Sunday's 6-4 victory over Detroit, making him the first player since Ray Chapman in 1917 to have multiple stolen bases in four straight games. He also set a franchise mark with a stolen base in six straight games, leads the AL with 36 steals and hasn't been caught in his last 23 attempts.
The second baseman is in nearly as impressive of a groove at the plate with a .510 average over his last 12 games, boosting his average to an AL-best .347 with an MLB-best 116 hits. The Astros are 18-17 in his multihit efforts and 3-12 when he's held hitless.
"I've seen some players locked in in all my years of playing," manager Bo Porter said. "But the impact with which Jose Altuve is having on the baseball game, I would have to really sit down and think about or have some numbers put in front of me that would make me think that there is someone who's had more of an impact on a baseball game the way he's having an impact right now."
Altuve is batting .393 with nine stolen bases and 14 runs scored over his last 14 games against Seattle, numbers he'll try to keep going in support of Collin McHugh.
McHugh (4-6, 2.86) has lost his last three starts, despite posting a 3.00 ERA and .185 opponent average. He's been given one run of support in 18 innings while striking out 21 over those starts.
He's 1-1 with a 4.22 ERA in two starts against Seattle.
Houston (36-47) is also coming off a series win - against first-place Detroit - and has taken three of its last four.
The Mariners have won eight of 10 in Houston.