SAN FRANCISCO -- Giants right-hander Johnny Cueto is scheduled to reach a key milestone in his rehab Wednesday, as he will face live hitters in Arizona for the first time since undergoing Tommy John surgery last August.

Cueto has resumed throwing all his pitches and could begin a rehab assignment next month, which would put him on track to return to the Giants' rotation in September. That could be a potential boon for a club that suddenly finds itself in the mix for a National League Wild Card spot.

"I love the progress he's made," manager Bruce Bochy said Tuesday. "I'm not going to be surprised to see him pitch in September."

A few of the Giants' other injured players are also progressing well. Third baseman Evan Longoria (left foot plantar fasciitis) is hitting off a tee and taking ground balls, while relievers Nick Vincent (right pectoralis strain) and Travis Bergen (left shoulder strain) are scheduled to make rehab appearances at Triple-A Sacramento. Bochy said Vincent will pitch Tuesday, followed by Bergen on Wednesday.

The Giants also brought center fielder Steven Duggar to Oracle Park on Tuesday in a taxi-squad capacity in case outfielder Alex Dickerson (right oblique tightness) experienced a setback during batting practice. Other than a pinch-hit appearance, Dickerson sat out the Giants' previous two games, but he returned to the lineup Tuesday and started in left field against the Cubs.

Pomeranz impresses in relief stint

Drew Pomeranz, who was removed from the rotation Sunday, made his bullpen debut for the Giants on Monday night, striking out four over two perfect innings in a 5-4 win over the Cubs. Pomeranz showed an uptick in stuff in the relief outing, touching 96 mph with his fastball.

"That was really impressive," Bochy said. "His first time in the 'pen, he goes out there and gives us two solid innings. He was the bridge to [Trevor] Gott. That was a really nice job he did, and he hadn't pitched in six, seven days. To go out there and have that kind of command on the curveball and the fastball, it's incredible."

Pomeranz's move to the bullpen could be temporary, as president of baseball operations Farhan Zaidi said he could see the 30-year-old veteran making more starts for the Giants down the stretch.