Sebastien Haller in training
Haller has not yet featured for Dortmund since joining from Ajax in July last year

Haller had surgery and was treated for cancer.

Haller signed a four-year deal with the team.

"It's been a tough six months but I'm happy to be here," Haller said.

Haller, who won the Ballon d'Or in October, is hoping to play in the first league match of the year.

"I am happy to be here with the guys and able to play in this great weather and these facilities."

Everything is doable. I don't have any restrictions in my thoughts. The coach and the medical staff are the only people who can tell me what I can and cannot do. I'm going to play on the 22nd.

The former Eintracht Frankfurt and West ham player scored 34 goals in a single season at the Dutch club.

After representing France at youth level, Haller went on to play for Auxerre and Utrecht, and then switched his loyalties to the Ivoirian coast.

After 15 games of the season, the team is ninth in the league, nine points behind the leader.