The Philadelphia Union are on the verge of adding some much-needed depth at goalkeeper.

Eintracht Frankfurt's Oka Nikolov is in talks to join the Union, a source with knowledge of the situation told Philly.com. Negotiations have reached an advanced stage, which means a deal could be done soon.

A native of Macedonia, Nikolov helped Eintracht finish in sixth place in the Bundesliga this past season. That was good enough for a spot in the 2013-14 Europa League. Nikolov played in 229 Bundesliga games and 34 German Cup games for Frankfurt, the only club of his pro career, since his debut in 1994. He has also won five caps for Macedonia's national team.

It appears that Nikolov would come here as a free agent. Eintracht chief executive officer Heribert Bruchhagen told the Associated Press on Tuesday that Nikolov's contract with the German Bundesliga club has been annulled with immediate effect at Nikolov's request.

The 39-year-old Nikolov has spent all 19 years of his professional career with Frankfurt.

"Throughout my career an opportunity to move to America and expand my horizons was always a dream of mine, and one which I hope to fulfill now," Nikolov said in a statement issued by the team.

Bruchhagen said he knew Nikolov wanted to come to MLS, though he did not specify which club Nikolov would be joining.

If Nikolov does come to Philadelphia, he would likely challenge Zac MacMath for the starting job. At the very least, he would be a consistent deputy to the Union's starter, and allow MacMath to take some breaks as the MLS season rolls on.

Since the start of 2012, MacMath has played every minute of all but two league games and one U.S. Open Cup game.

Lack of depth in net has been a particular concern this year, as the Union have only carried two goalkeepers on their roster instead of the usual three. Backup Chris Konopka has only seen time in friendly games.

It's not the first time Nikolov has eyed a move to the U.S. He was a free agent in 2010, and was linked with the New York Red Bulls. But he re-signed with Frankfurt and stayed there until now.