Lasith Malinga is in serious doubt for Sri Lanka's tour of England with what doctors are now describing as a 'substantial' knee injury.

Sri Lanka kick off their Test series against England on May 19 but Malinga has already retired from that format. The one-day series starts on June 21, giving him an extra month to return to fitness.

Malinga had already been ruled out of the entire Indian Premier League (IPL) season with the injury and, although scans have shown he will not necessarily need surgery, a speedy return appears unlikely.

Malinga suffered the injury during West Indies’ tour of Sri Lanka last November and has only played one competitive game since, missing the World Twenty20 in India as well.

Sri Lanka Cricket medical committee chairman Dr. Harindu Wijesinghe said, 

“
Malinga is suffering from a stress reaction in the knee.

”

 
"This has been caused by pressure being put on the knee. There is a chance that a stress reaction could worsen to a stress fracture, at which point he would need surgery. A few doctors have been advising Malinga, and we feel that he needs to rest his knee, while undergoing physiotherapy and strengthening.”

After the England tour there is also ODI and T20 cricket against Australia scheduled for August, but Malinga appears in doubt for those series as well.