USA No.1 Zack Steffen can become one of Europe's best goalkeepers, according to Fortuna Düsseldorf sporting director Lutz Pfannenstiel.
The 24-year-old has been one of few plus points during a difficult campaign for the Bundesliga's bottom side, but they would arguably be a lot worse off without him.
Despite sitting out recent back-to-back defeats to Werder Bremen and Bayer Leverkusen with knee trouble, the former Columbus Crew netminder has made the fourth-highest number of saves in the league this season (67).
Pfannenstiel, a goalkeeper in his own playing days, has been suitably impressed.
"Zack had a brilliant start into the season and showed that he has the potential to become a top 'keeper at the European level," Pfannenstiel told Transfermarkt. "Steffen has all the ingredients. He has a very clean goalkeeper technique. Good reactions, good hands, and demanding in the box. His distribution and game-opening make him a modern 'keeper.
"Looking at all that, it is not a surprise that Manchester City went for Zack."
While Pfannenstiel has also said that Düsseldorf would "have to sell our stadium" to finance a permanent move for Steffen, CEO Thomas Röttgermann has intimated an extended loan deal could be a possibility.
"Just because there's no purchase option, does not necessarily mean that we lose Zack Steffen at the end of the season," he revealed earlier in the campaign.
Steffen has himself said he is open to staying, as long as Fortuna can avoid relegation to the second tier.
"Extending my contract here would only be an option if we stay in the Bundesliga," he told Bild in early January. "As a young goalkeeper, I need games and experience at the top level. That's what I'm getting at Fortuna. I have a good thing here."
Watch: Zack Steffen reflects on his first half-season in the Bundesliga
Steffen, who previously played for the Freiburg reserves and has since gone on to earn 17 USMNT caps, is expected to return to the Düsseldorf starting line-up for Saturday's home game against Eintracht Frankfurt.
It will be his first competitive outing of 2020, and the club's first under new head coach Uwe Rösler following Friedhelm Funkel's dismissal earlier in the week.
Fortuna are currently two points adrift of the relegation play-off spot and three behind outright safety, following a run five defeats in their last six.
After Frankfurt, they face 3. Liga side Kaiserslautern in next week's DFB Cup third round.