Sri Lanka’s captain Angelo Mathews celebrates after they win over the first test cricket match against Pakistan in Galle. (Source: Reuters)

Left-arm spinner Rangana Herath claimed six wickets as Sri Lanka fashioned an unlikely seven-wicket victory over Pakistan to go one-up in the two-test series on Sunday.

Herath took six for 48 as Pakistan crumbled to 180 allout in their second innings, leaving Sri Lanka to chase 99 for victory in 21 overs in a contest that looked to be heading for a draw at the start of the final day.

Sri Lanka got there with 4.4 overs to spare with skipper Angelo Mathews, who hit an unbeaten 25, stroking the winning runs to spark off celebrations around the ground.

Herath cleaned up the Pakistan tail, leaving Sarfraz Ahmed unbeaten on 52, his second half-century of the match.

The second test starts in Colombo on Thursday and will be the final appearance of former Sri Lankan captain Mahela Jayawardene in the longer form of the game.