Manchester City's Ilkay Gundogan says "disrespectful" Manchester United would undoubtedly be better with Bastian Schweinsteiger.
Schweinsteiger has been left out of United's first-team plans under Jose Mourinho, having been signed by former manager Louis van Gaal, and has even been written off as an asset in the club's latest published accounts.
The 32-year-old World Cup winner has already received the support of former Germany team-mate Lukas Podolski, and now Gundogan, City's summer signing who played alongside Schweinsteiger for the national team, has also criticised United's handling of the player.
"I believe that Manchester United could 100 per cent benefit from a fit Bastian Schweinsteiger," Gundogan told Sport Bild.
"If everything you hear and read is true, you can consider it disrespectful. He's not just some player, and also not only 18 or 19."
Gundogan has played in City's last three Premier League games after returning from a serious knee injury and has backed himself to replace Schweinsteiger for Germany following the United midfielder's retirement from international football.
"I trusted myself to do that before [Schweinsteiger's retirement], but this has nothing to do with saying his retirement is positive or negative," he said. "We should be thankful that we had such a great player."