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3/2/2013 3:50 P.M. ET

Martinez, Pena go deep for first time this spring

KISSIMMEE, Fla. -- Right fielder J.D. Martinez hit a two-run homer in a four-run outburst in the fourth inning that lifted the Astros to a 6-5 win over the Braves on Saturday afternoon at windswept Osceola County Stadium.

Martinez, last year's Opening Day left fielder who's battling for a spot on the club, crushed a pitch from Braves left-hander Sean Gilmartin and sent it over the left-field wall to break a 1-1 tie. Jose Altuve added an RBI double later in the inning. Fernando Martinez had an RBI single earlier in the inning.

Carlos Pena hit a solo homer for the Astros in the first inning off Braves starter Kris Medlen, and Freddie Freeman homered for the Braves in the third off Philip Humber.

A fielding error by Marwin Gonzalez on a ball hit by Chris Johnson helped open the door to a three-run Braves seventh. After Gerald Laird walked, Joey Terdoslavich singled home Johnson. Following Ramiro Pena's walk, pinch-hitter Jordan Parraz grounded into a double play, which scored Laird and moved Terdoslavich to third. Todd Cunningham followed with a single to score Terdoslavich.

Lefty Dallas Keuchel got the start for Houston and gave up three hits and no walks in two scoreless innings. Humber followed and allowed two hits and one run while striking out three batters in three innings.

"It was just nice to get my focus that first time out [as a starter]," Keuchel said. "I kind of was everywhere mentality wise [during Monday's rough relief outing], and this time out I tried to really focus on the mental side. ... I got myself ready, and I think it was a lot better," Keuchel said.

Medlen allowed one hit and one run over three innings.

Up next: John Ely, who pitched two innings in relief in his only spring outing on Tuesday, gets the start for Houston when it travels to Bradenton, Fla., to face the Pirates at 12:05 p.m. CT. Ely is competing for a spot in the rotation. Jordan Lyles, Sergio Escalona, Sam Demel, Chia-Jen Lo and Jose Valdez are also scheduled to pitch.

Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.