RB Leipzig and USA midfielder Tyler Adams is no closer to making his return to full first-team training and could miss the start of the new season, according to German media reports.

Adams sat out five of Leipzig's final six games of the 2018/19 Bundesliga season with a troublesome groin injury.

He returned to face Bayern Munich in the DFB Cup final on 25 May, before a recurrence of the problem forced him to withdraw from the USMNT's 2019 CONCACAF Gold Cup squad earlier this summer.

The 20-year-old was expected to return to action at the end of July, but is still undergoing an individual treatment programme and cannot yet partake in team training.

"Our medical department are doing everything they can, but Tyler's injury is complicated," new Leipzig coach Julian Nagelsmann told German daily, Bild. "Suddenly you're pain-free and expect to get involved again, but it's misleading."

Adams' continued absence is a real blow to Nagelsmann as he steps up preparations for his debut season as Leipzig coach.

The former New York Red Bulls midfielder was one of the standout performers of the 2018/19 Rückrunde, despite only joining Leipzig in January.

Making a seamless transition from Major League Soccer to the Bundesliga, he went unbeaten in his first nine league appearances before the final-day loss to Werder Bremen, and ended the campaign with two assists and an impressive average of 86 per cent for passes completed.

Watch: Tyler Adams on his first impressions of RB Leipzig

With no concrete return date in mind, however, Adams will have to wait to build on those impressive figures.

The 10-time USMNT international will almost certainly miss the pre-season friendly against English Premier League side Aston Villa on 3 August, and is unlikely to be available in time for Leipzig's DFB Cup first-round meeting with VfL Osnabrück on 11 August.

Leipzig, who finished third in last season's Bundesliga and also have UEFA Champions League group-stage football to look forward to, begin their league campaign away to promoted top-flight newcomers Union Berlin on 18 August.