SAN FRANCISCO -- Giants left-hander Drew Smyly departed his start against the Rangers on Saturday in the fifth inning with left index finger discomfort and will undergo an MRI exam on Sunday.

Smyly, 31, took the mound in the fifth and threw two pitches to Texas designated hitter Rob Refsnyder before third baseman Evan Longoria jogged over to the mound to check on him. Manager Gabe Kapler and athletic trainer L.J. Petra soon emerged from the dugout to evaluate Smyly, who attempted to throw a few warmup pitches before walking off the field.

Right-hander Shaun Anderson was summoned to replace Smyly on the mound and ended up combining with four other relievers to secure a 7-3 Giants victory.

Smyly exited after throwing 71 pitches, costing him a chance to become the first Giants starter to complete five innings this season. He struck out seven and allowed two runs over four-plus innings, with the only damage coming on Todd Frazier’s two-out, two-run single in the first inning.

Catcher Tyler Heineman said he didn’t detect any discomfort from Smyly prior to the fifth inning. 

“He didn't say anything,” Heineman said. “His stuff was really good, so I didn’t notice anything. I thought he threw the ball incredible. He made his pitches. His curveball was good. His fastball location was good. He coupled those two pitches with his slider, down and in and a couple backdoor. I thought he was really sharp. I feel for him. I came in midgame to check to see how he was doing. Looks like he’s doing OK.”   

Through their first nine games of the year, the Giants have yet to have one of their starting pitchers make it through the fifth, the longest such streak to start a season in MLB history, according to Stats LLC. Right-hander Kevin Gausman delivered the longest outing by a San Francisco starter thus far, tossing 4 1/3 innings against the Padres on Thursday.