PHOENIX -- Manager Bruce Bochy and an assortment of Giants players, coaches and athletic trainers gathered around the visiting bullpen at Chase Field on Saturday afternoon. Only one person toed the rubber on the mound -- right-hander Johnny Cueto.

Cueto, who underwent Tommy John surgery last August, started a throwing program in late April at the Giants' facilities in Scottsdale, Ariz. He threw his first bullpen session on April 30, and his session prior to Saturday's game against the D-backs was his fifth.

However, this was the first time Bochy and his staff had a front-row seat for the action, as Cueto came to visit the team and throw in front of the trainers. And the skipper was impressed with what he saw from the 33-year-old veteran.

"He threw really, really well," Bochy said. "I think he surprised a lot of us with where's he at, as far as his stuff, how hard he was throwing, command. It's all fastballs. He's gotten himself into great shape, too. I think it's the best shape I've seen Johnny in, to be honest. He just looks very determined to get back as soon as possible."

Cueto said he has lost 20 pounds and currently weighs 224. He has been losing fat and gaining muscle, and he hopes to put on more muscle to get up to around 230.

"Right now, I feel like a 25-year-old kid," Cueto said through an interpreter.

In Cueto's first bullpen session, he threw 20 pitches. He threw 30 in his second and 40 in each of his last three, including Saturday. He has only thrown fastballs, but he is also throwing changeups off flat ground. Cueto will start mixing sliders and curveballs into his sessions in two weeks.

Cueto made only nine starts last season, going 3-2 with a 3.23 ERA. He made five starts in March/April, then missed two months with right elbow soreness. The righty returned for four July starts, but he was shut down after his July 28 outing and underwent Tommy John surgery on Aug. 2.

It typically takes pitchers 12 to 18 months to come back from Tommy John surgery. Cueto could return in September, which would be 13 months after his operation.

"You've got to believe that he's going to be pitching before the season's over," Bochy said. "Everybody's a little bit different as far as their rehab, their ability to pitch in a live game. Some guys take a little bit longer than others. But I'm just saying, when you watched him today, he's further along than we all thought he would be."

Cueto is also optimistic he'll be pitching for the Giants later this year. However, if the team later decides to take a more cautious approach, he'll understand.

"I want to pitch in September. Right now, I feel really good," Cueto said. "My main concern is I want to come back good. So, whatever decision they make, I'm good with it."

Pomeranz coming off IL

Left-hander Drew Pomeranz will come off the injured list to start Sunday's series finale against the D-backs. He went on the IL with a left lat strain on May 9 and threw a four-inning simulated game against Giants hitters on Tuesday.

"He's good to go," Bochy said.

Pomeranz is 1-4 with a 5.93 ERA in seven starts this season. He allowed seven runs in 1 2/3 innings in his last start on May 6 against the Reds.

The Giants will need to make a roster move to clear a spot for Pomeranz.