Tottenham boss Jose Mourinho has said he expects forward Son Heung-Min to miss the rest of the campaign, with the South Korea international set to have surgery after suffering a fractured arm, the club have announced.

The news will come as a huge blow to Spurs who are already without fellow forward Harry Kane until April, due a hamstring injury.

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And, while Tottenham initially stated they expected Son to be out for "number of weeks," Mourinho said he was far less optimistic.

"I'm not going to count on him again this season," he told a news conference ahead of their Champions League round-of-16 first-leg clash with RB Leipzig.

"If he plays two or three games then it's because he [Tottenham's press officer] is very optimistic, but I'm not counting on him."

Mourinho also said Son's absence is likely to mean a change in system.

"The situation couldn't be worse in terms of options," the former Chelsea and Manchester United boss added. "It's a very, very obvious situation.

"There is nothing that you can do. We are going to play with the players that we have available. The players are going to give everything, which is what they are doing. In some periods I was worried about not having attacking options on the bench, now it's not having attacking options on the pitch."

Son reportedly suffered the injury early on in the 3-2 win over Villa, in which he scored two goals -- including a last-gasp winner.

Tottenham are still fighting on three fronts as they host Leipzig on Wednesday, before welcoming Norwich on March 4 in the FA Cup fifth round.

In the Premier League, they sit fifth -- one point behind fourth-place Chelsea -- with games against the Stamford Bridge side as well as other rivals for Champions League qualification in Wolves and United to come in the next few weeks.