Darvish is 0-3 his last five starts, all Rangers losses. The Japanese right-hander struck out six while allowing one run and four hits over seven innings. He threw a season-low 81 pitches before coming out because of cramping in his right leg.
Manager Ron Washington said the move was precautionary.
"We needed him to step up and he stepped up tonight, he really threw the ball well, he moved the ball around well, he kept it down in the zone, he did a good job," Washington said. "He's in great shape. It's just something that flared up. If that's all that's wrong with him, and the way he pitched out there tonight, I'll take it."
Cole got out of a self-induced jam in the sixth after consecutive walks to Elvis Andrus and Alex Rios, his only walks in the game. Andrus got his 38th career stolen base — the Rangers pulled off a double steal when Rios reached before Adrian Beltre grounded out.
"The sixth inning could have gotten out of hand," Cole said. "I was just able to get the ball down on them."
Tony Watson pitched a perfect eighth, his 14th consecutive scoreless outing. Mark Melancon worked the ninth for his 12th save in 14th chances to close out Pittsburgh's 16th shutout of the season.
The Rangers said Darvish started feeling the cramps during the seventh. There was a short delay after the Rangers took the field in the eighth before Tanner Scheppers came out of the bullpen.
"It's minor," Washington said. "No level of concern."
NOTES: It was the 14th 1-0 game ever at Rangers Ballpark, which is in its 20th season. It was the second this season, both Rangers losses. ... Pirates CF Andrew McCutchen had a leadoff triple in the ninth. He was thrown out trying to score on Justin Morneau's chopper to second baseman Ian Kinsler. ... Rangers LF Jim Adduci left the game after his at-bat in the fifth inning, when he sustained a right biceps strain while striking out. ... Darvish upped his major league-leading strikeout total to 246. ... Beltre was 1 for 22 over six games before his two-out single in the ninth.
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