Arsenal manager Arsene Wenger's only signing of the January transfer window, 31-year-old Swedish international Kim Kallstrom, has picked up a back injury in his first training session for the Gunners, and faces up to three months on the sidelines.
The BBC reports that Kallstrom's injury is still being assessed by Arsenal's medical staff. Kallstrom was signed as cover in case of injury to Aaron Ramsey, Jack Wilshire or Santi Cazorla, but now faces a lengthy spell on the sidelines himself.
The 31-year-old player signed on loan from Spartak Moscow on Friday until the end of the season.
Kallstrom has made 108 international appearances for Sweden and over 400 club appearances since making his debut in 1999 for Swedish side BK Hacken.
Following two years at Djurgardens IF, Kallstrom, moved to France where he spent eight successful years, firstly with Rennes for two seasons, before moving to Lyon.
During his time with 'OL', Kallstrom made over 200 appearances, winning the Ligue 1 title twice (2006/07, 2007/08), the French National Cup twice (2008, 2012) and the French Super Cup twice (2007, 2008). He was also a regular in the Uefa Champions League, helping Lyon to the semi-final of the competition in 2009/10.
The midfielder has represented his country at four major tournaments - the European Championships in 2004, 2008 and 2012, and the 2006 World Cup.
His time at Arsenal already looks likely to prove less fulfilling. Kallstrom barely had time to give a first interview to the Arsenal website before incurring his injury.
Though early reports claimed that Kallstrom could be out of the first-team picture at his new club for up to three months, an Arsenal press officer has been quoted by Swedish newspaper Aftonbladet as saying: "Kallstrom has hurt his back and he is currently under investigation. Arsenal will talk about it tomorrow. But I think two or three months is a little excessive."