U.S. national team attacker Aron Johannsson is set for a longer spell on the sidelines after undergoing successful hip surgery in Berlin, his club Werder Bremen said on Wednesday.

Johannsson, 24, joined Bremen from AZ Alkmaar this summer and following six appearances and two goals for the Bundesliga club had already been sidelined since late September.

While at first it appeared the attacker picked up a groin injury, further examinations showed a nerve irritation in his right hip. Following an unsuccessful non-surgical treatment, the club decided Johannsson needed surgery to be able to become pain-free again.

"We have exhausted all non-surgical treatment options and have not been able to reach a sustainable analgesia," club doctor Philip Heitmann was quoted as saying on the club's official website.

The club tweeted a photo of Johannsson post-surgery on Wednesday.

Aron Jóhannsson ist heute Morgen erfolgreich an der Hüfte operiert worden. Gute Besserung, @aronjo20 pic.twitter.com/NtbBkjgbmp - SV Werder Bremen (@werderbremen) October 28, 2015

On Wednesday, Johannsson underwent surgery in Berlin, where he will stay for a few more days before resuming rehab training in the next few days, the club said.

"The Green & Whites will be without the 24-year-old for the next weeks," the statement read.