(Sports Network) - The Houston Astros close out a disappointing first half of the season with this afternoon's rubber match of a three-game series with the host Washington Nationals.

Houston will enter the All-Star break in last place in the National League Central standings and has particularly struggled in July, as the team has won just three times in 11 games so far this month. The Astros have earned victories in two of their last three matchups, however, following Saturday's 6-4 triumph over the Nationals.

Hunter Pence went 2-for-3 with a homer and three runs batted in to pace Houston offensively, while Carlos Lee ended with three hits and collected his 73rd RBI of the season in the win.

Astros starter Wandy Rodriguez (4-3) worked the first 5 1/3 innings and allowed four runs on eight hits, but three Houston relievers combined to hold Washington scoreless the rest of the way and protect the lead. Jose Valverde finished things off with a 1-2-3 ninth for his 24th save of the year.

Houston improved to 3-5 on a current nine-game road trip and 21-30 as the visitor this season.

Willie Harris had two hits, including a solo home run, for Washington, losers of eight of their last 10 games. Jesus Flores knocked in a pair of runs in defeat.

Nationals rookie Collin Balester (1-2) lasted just 4 2/3 innings and surrendered six runs (4 earned) and 11 hits.

Today's finale pits two pitchers that are both coming off shortened outings in their last starts in Washington's Odalis Perez and the Astros' Brandon Backe.

Perez's start was curtailed after just 2 2/3 innings when the veteran lefty was ejected for arguing a balk call against him in Tuesday's matchup with Arizona. He had allowed an unearned run prior to being removed from the game, and that was enough for Perez to receive a tough-luck loss in the Nationals' 2-0 setback to the Diamondbacks.

The 31-year-old has pitched very well in three starts following a 3 1/2-week stay on the disabled list, although he hasn't been able to garner a victory since being activated. In those three appearances, Perez has surrendered only three runs -- two earned -- and nine hits over a combined 13 1/3 innings of work.

Houston has hit the native Dominican hard over the course of his career, with Perez bringing an 0-4 record and an ugly 11.57 earned run average over seven games (6 starts) against the Astros into today's tilt. He faced Houston back on May 7 and recorded a no-decision after giving up three runs through five innings.

Backe threw three shutout innings against Pittsburgh on Tuesday before having his night prematurely end due to a long rain delay. It was still an encouraging showing for the right-hander, who had been roughed up for 11 runs over 12 frames in consecutive starts against Boston and the Los Angeles Dodgers heading into that game.

The oft-injured hurler has lost four of his last five decisions and has served up 22 home runs in his 19 starts, the second-highest total in the National League this year.

Houston won two of three matchups with the Nats at Minute Maid Park back in May, but Washington is 10-5 in its last 15 clashes against the Astros. Houston has also lost six of its last eight in D.C.