Union center back Josh Yaro has yet to play after shoulder surgery on Feb. 7, but he has taken a big step toward his comeback by returning to full contact in practice.

"I am excited to be back playing again and waiting to heal fully so I could get back fully," he said after Wednesday's training session.

Before returning to MLS action, Yaro said he expects to first spend time with the Union's United Soccer League affiliate, the Bethlehem Steel.

Coach Jim Curtin estimated that Yaro would return in early June and said it hasn't been determined whether it will be with Bethlehem or the Union.

Earlier in the season, when the Union were struggling, there appeared to be more urgency to have Yaro return. But the defense, and the team in general, have turned things around, winning four straight, going unbeaten in six consecutive games and allowing just one goal in the last five contests.

Yaro, the No. 2 overall pick in the 2016 draft from Georgetown, would provide the speed that the Union are missing at the center back position.

The recent pairing at center back of 35-year-old Oguchi Onyewu and rookie Jack Elliott, has worked well.

Onyewu, who has started four straight games, returned to training on Wednesday. Curtin said he was supposed to come back on Thursday due to inflammation in his back but felt better and returned a day early.

The 22-year-old Yaro appeared in 17 games, making 15 starts last season. He missed time with a shoulder injury and a concussion.

Midfielder Fabian Herbers, who suffered a groin injury in Saturday's 2-1 win over the Colorado Rapids, is out indefinitely. Curtin says a best-case scenario is he can return in two weeks, and a worst-case is a month.

Midfielder Roland Alberg, who missed the last three games with a quadriceps strain, hasn't returned to training. It doesn't appear likely he will play this week, but Curtin wasn't ready to rule him out.

The Union (4-4-4) will depart on Thursday after training for Saturday's game at Real Salt Lake (3-8-2).

mnarducci@phillynews.com

@sjnard