Lasith Malinga has offered to step down as Sri Lanka's T20 captain, after concerns over the slow recovery of a knee injury have grown. The board is yet to make a final call on whether a change of leadership is needed, but Malinga has handed the board a letter voicing reservations about keeping the job when he cannot guarantee his availability for Sri Lanka's full campaign.

An MRI scan on Monday confirmed substantial damage to Malinga's knee, but also suggested that he could manage the injury with painkillers over the next few weeks. The team is scheduled to leave for India on Tuesday, but Malinga is considering staying in Sri Lanka to receive further treatment. He may not depart to India until the days before Sri Lanka's first match, on March 17.

This overuse injury to the left knee - on which he lands during the delivery stride - has troubled him since West Indies' series in Sri Lanka in November last year. He missed Sri Lanka's tour of New Zealand in December and January, and was later ruled out of the T20s in India, in February. Then, Malinga played only one match of four during the Asia Cup, taking four wickets in Sri Lanka's solitary victory against UAE, before sitting out games against Bangladesh, India and Pakistan. It is understood he has not bowled in the nets since the UAE game, though, he is not a player who generally requires extensive net bowling before matches.

The recovery date for this injury has always been vague, but has been much slower than initially expected, prompting particular worry. It was hoped Malinga could be fit for the T20s in New Zealand, and he was picked for the Asia Cup on the understanding he could play a substantial role in that tournament.

This is also the third serious injury to hit Malinga's career. He had previously been plagued by a similar overuse injury in his right knee, which he said forced him to retire from Tests in 2010. Then in 2014, a long-term ankle injury was operated on in the months leading up to last year's World Cup. It now appears possible that this current injury could end his international career. In the approach to the Asia Cup, Malinga had hinted the World T20 might be his final foray for Sri Lanka.

Angelo Mathews appears the likeliest captaincy candidate if Malinga does step down, though Dinesh Chandimal is also an option. Malinga's potential absence as a bowler is perhaps the bigger blow to Sri Lanka's campaign. He has been instrumental to Sri Lanka's march to three World T20 finals over the last four tournaments, and is also the World T20's most successful bowler. He has been a diminished threat since his ankle surgery in 2014, but remains - at least in spirit - Sri Lanka's limited-overs spearhead.