ARLINGTON -- After throwing just 74 pitches and five shutout innings, Matt Harrison was taken out of Sunday's game against the Rockies with what team doctor Keith Meister called lower back tightness in his left side.
Harrison, who picked up his American League-leading 10th win Sunday, is confident that he will make his next start, Friday against the Athletics. It would be Harrison's first start against an AL team in nearly a month. He went 3-0 with a 0.33 ERA in four Interleague starts, improving to 5-2 in his career against the National League.
"When I went out for the third inning, I was a little stiff in my lower back," Harrison said. "I ended up telling them what was going on and they decided to be cautious with it and shut it down to make sure I'm ready for next start and I don't blow out anything."
Harrison said he felt better by the time the third inning was over, but the stiffness re-emerged before he took the mound in the fourth. The 74 pitches, including 49 strikes, were a season low. He gave up five hits, struck out three, and walked two in the Rangers' 4-2 victory.
"Harrison did not want to come out," manager Ron Washington said. "We weren't taking any chances. It's no big deal. He will make his next start."
With the victory, Harrison improved to 10-3 on the season and lowered his ERA to 3.24. He is 6-0 with a 1.29 ERA in his last seven starts and tied the team record for most wins through the Rangers' first 73 games. Harrison, who induced double plays in each of the final three innings he pitched, became the first Rangers pitcher to surrender fewer than two runs in four straight starts since Scott Feldman in 2009.
"I'll definitely take the wins any time I can get them," Harrison said. "I didn't really have my best stuff working today, but I kept telling myself when guys were on base that I was one quality pitch away from getting out of it. I was able to bear down and get out of some innings."
Rookie Robbie Ross replaced Harrison on the mound in the sixth inning and did not allow a run in his 10th straight outing. Ross, who turned 23 on Sunday, has not allowed a run in his last 15 2/3 innings and hasn't given up an earned run in 23 straight innings.
Tanner Scheppers pitched a scoreless seventh inning and Mike Adams kept the Rockies from scoring in the eighth.
For the first time since May 13, Joe Nathan gave up a run in the ninth inning, breaking a consecutive scoreless inning streak at 16 but securing the win, the Rangers' eighth in nine games.
"I'm not very happy about being a five and done guy, but, in that situation, I had to come out," Harrison said. "The most important thing is that we came out with a win tonight. We've been on a roll lately so hopefully we can keep it going."
Christian Corona is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.