Borussia Dortmund's star signing Henrikh Mkhitaryan set to miss season's start

Champions League finalists Borussia Dortmund expect to be without new signing Henrikh Mkhitaryan for the start of the new Bundesliga season on August 9 after the midfielder tore ankle ligaments.

The 24-year-old, who cost Dortmund 27.5 million euros ($36 million) from Shakhtar Donetsk, scored in Dortmund's 4-1 win over FC Luzern on Tuesday but tore ligaments in his right ankle, meaning he is expected to be out for up to four weeks.

Mkhitaryan will miss the German Super Cup clash with Champions Leaguer winners Bayern Munich at home on July 27, plus the league season opener against Augsburg on August 10, but is expected to return the week after, the club confirmed Wednesday.

Dortmund are in the midst of their pre-season training and play in a four-team tournament this weekend which includes Hamburg, hosts Borussia Moenchengladbach and European Cup-winners Bayern.

Meanwhile, Dortmund's want-away striker Robert Lewandowski has admitted he faces another season at Borussia with his contract due to expire in June 2014.

The 24-year-old has made no secret of his desire to move to a bigger club, with strong rumours he will join Bayern, but Dortmund have received no offers for the Poland hot-shot.

"I have to accept that I must stay in Dortmund," Lewandowski told German daily Bild.

"I played and scored in the knowledge that I was allowed to leave in the summer."

Lewandowski, who scored four goals in the Champions League semi-final, first leg win over Real Madrid in April, said talks with Dortmund had led him to believe he could change clubs.

His agent and manager were quoted on numerous occasions saying a move to a big club was imminent at the end of the season but Borussia received no offers for the striker and will hold the Poland star to his contract.

Bayern chairman Karl-Heinz Rummenigge last week said of Lewandowski: "I am quite optimistic that the player will move to Bayern next summer."

But Dortmund coach Jurgen Klopp has said Lewandowski is working hard in training.

"He couldn't be more professional," said Klopp after Lewandowski scored in last week's friendly win against Turkish side Bursaspor and then on Tuesday at FC Luzern.