PAWTUCKET, R.I. (AP) – Jon Lester pitched five scoreless innings Tuesday night for the Pawtucket Red Sox against the Columbus Clippers and left the game with a 4-0 lead.

Columbus rallied against Pawtucket’s bullpen for a 5-4 victory. Lester allowed four hits plus two walks and matched his season high with six strikeouts. He threw 79 pitches, including 50 for strikes.

“Early on I struggled with my mechanics and had to battle through a couple of innings but as the game went on everything got a little tighter and a little better,” Lester said.

“We want to get better every start and get the pitch count up,” he continued. “This time it just happened to be the curveball that worked well. Next time, it may be the changeup or the fastball.”

In his previous start, on May 24 against Syracuse, Lester was prohibited from throwing his cut fastball because Boston’s medical staff felt it might have contributed to cramping in his forearm that he suffered on May 2 against Indianapolis.

“I threw two of them tonight and felt fine,” Lester said of his cutter. “I’m sure they’ll increase the numbers as we go on.”

After his latest start, Lester is 0-1 with a 1.24 ERA, seven walks and 19 strikeouts in 21 2/3 innings. He’s also allowed only 14 hits.

Mike Timlin (shoulder tendinitis) made his third relief appearance during his current 30-day rehab assignment and struggled through the seventh inning, which began with Pawtucket leading 4-2. He allowed one run on three hits and a walk, and only threw 13 of 23 pitches for strikes.

AP-ES-05-30-07 0018EDT