When backup Union right back Olivier Mbaizo suffered a torn meniscus late last month, the team found itself in sudden need of depth at the position.

A call went out to RJ Allen, a four-year MLS veteran who was out of contract after being waived by Orlando City in February. Allen had spent the last few months with a semipro team in his native northern New Jersey, and didn’t hesitate when given a chance to return to the top flight. He trained in Chester for a week, and the Union liked what they saw enough to sign him for the rest of the season.

“I’ve shown that I’m fit and I’m ready to play,” Allen said as he was officially introduced after Tuesday’s practice. “I’ve been kind of sitting, just keeping myself busy, keeping myself fit, waiting for an opportunity.”

The 29-year-old said he’s been impressed with the Union’s chemistry, and with the results that have his new team atop the Eastern Conference at the start of July.

“Great group of guys, really fun to be around,” he said. “They are where they are in the table for many reasons. The locker room is probably one of the main [ones]. It’s a really special group, and I sensed that as soon as I walked in.”

Allen spent last year in Orlando, and three seasons before that with New York City FC. He began his professional career in Denmark’s second division in 2013 after spurning a draft pick by Chivas USA in 2012.

In his time in MLS, Allen has recorded 13 assists and one goal in 71 appearances. He is eligible to play immediately, which means his Union debut could come against his last team. The Union play at Orlando on Wednesday (7:30 p.m., PHL17), and host the Lions on Saturday (7 p.m., 6ABC).

“[Allen] has been doing a good job staying in shape, still playing, and at the same time has quickly impressed the staff with his ability to defend [and] to communicate,” Union manager Jim Curtin said after Tuesday’s practice. “We just wanted to have some stability there if there is an injury to Ray [Gaddis]. I’m fully confident putting him into a game as soon as tomorrow.”

While gaining Allen, the Union will likely be without sparkplug winger Ilsinho on Wednesday after he suffered a minor knee injury in last Saturday’s loss at New York City FC.

“It’s not going to be long-term,” Curtin said. “We’ll see if he can turn it around for [Wednesday]. I’m optimistic that he’ll certainly be fine for Saturday at the latest.”