KISSIMMEE, Fla. (AP) -- Brett Wallace would be at the top of the list of players most likely to start the season at first base for the Houston Astros.

Wallace started at third base Tuesday in the Astros' 9-4 exhibition victory over the Detroit Tigers, then moved over to first base for three innings after hitting a home run and a couple of singles.

''I'm really comfortable at both,'' Wallace said. ''I just come in, look at the lineup, see where Bo wants me and go from there.''

New manager Bo Porter is still deciding who will play where.

''When you look at our roster and the way it's constructed, it gives us good flexibility and good balance when you have a guy who can play first base, third base and can also DH. I like to have that flexibility,'' Porter said.

The 26-year-old Wallace has played in 232 games for Houston, more than any other player on the in-flux roster. The Astros signed Carlos Pena in December, but the former Gold Glove first baseman is probably going to DH against right-handers in Houston's first American League season.

Wallace knows that if he hits, Porter will find a place for him in the lineup. On Tuesday, he was most pleased with his sixth-inning single off Michael Morrison, which came on a changeup.

''It's a rhythm and timing thing,'' Wallace said. ''We have been in the cage working quite a bit, just trying to get to a point of comfort where I'm . . . down with seeing pitches and recognizing them and putting good swings on them.''

Jason Castro also homered for the Astros, who broke the game open with a five-run fifth inning off Duane Below. Robbie Grossman and Trevor Crowe drove in four runs on back-to-back extra base hits in the big inning.

Bruce Rondon, the Tigers' rookie closer candidate, walked two and struck out two before being taken out of the game in the third inning, having thrown 22 pitches.

Rondon was wild in his second spring appearance. He said the wet mound and steady drizzle were not major factors.

''Not really. A little bit, but it's not an excuse,'' he said. ''Sometimes the pitches are just not there, but I still felt fine.''

Erik Bedard pitched two innings in his first start for the Astros, giving up an unearned run on Wallace's throwing error.

''I came out throwing strikes and we got some good defense,'' said the 34-year-old Bedard, who was 7-14 in 24 starts with Pittsburgh last season. ''I'm changing speeds and throwing the ball down, and location is always the key. If you can do that every time out, you're going to be successful.''

Brayan Pena's two-run homer off winning pitcher John Ely gave the Tigers a brief 3-2 lead in the fourth.

Doug Fister gave up the two-run homer to Castro in his two-inning start for Detroit.

NOTES: The other half of the Astros' split squad lost 7-2 to Tampa Bay in Port Charlotte. ... Quintin Berry (patella tendinitis) was added to the list of injured Tiger outfielders, joining Brennan Boesch and Andy Dirks. None of the injuries is believed to be serious. ... Alex White is scheduled to make his first spring start for the Astros on Wednesday against Toronto. White, who started 20 games for Colorado last season, is one of six main candidates for the five starting slots.