NEW DELHI: Sri Lanka sealed their spot in the T20 tri-series final after a tense six-run win over Pakistan on Thursday, thanks to a brilliant last over from Dushmantha Chameera. The fast bowler delivered a match-winning spell of 4 for 20, shutting down Pakistan's chase when it mattered most.

Pakistan, unbeaten in their previous three games and already assured of a place in Saturday's final, finished at 178 for 7 despite a valiant, career-best 63* from captain Salman Ali Agha.

Earlier, opener Kamil Mishra set up Sri Lanka's total with a fluent 76 off 48 balls, steering his side to 184 for 5 - a score they had to defend to knock Zimbabwe out of contention and keep their own campaign alive.

"Proud of how the boys bounced back," Sri Lanka captain Dasun Shanaka said. "Everybody contributed. … Of course Chameera (exhibited) world-class bowling."

Chameera wrecked Pakistan's chase early with a sensational power-play burst of 3 for 3, and later iced the game by giving away just three runs in a tense final over when Pakistan needed 10 to win.

The lanky pacer outfoxed Sahibzada Farhan (9) with a clever slower ball that was chipped to short cover, before trapping star batter Babar Azam lbw for a two-ball duck, leaving Pakistan stunned.

Left-handed batter Saim Ayub (27) once again couldn't convert his aggressive start off 18 balls before he dragged Eshan Malinga back onto his stumps. Chameera had Pakistan on the mat at 4-43 in the sixth over when Fakhar Zaman holed out at mid-on.

Agha and Usman Khan (33) put the chase back on track with an aggressive 56-run stand before Wanindu Hasaranga broke through in the 13th over and Khan sliced a catch to short third.

But Agha and Mohammad Nawaz (27) cut lose in the death overs with a rapid 70-run stand off 36 balls before Malinga struck in the penultimate over and had Nawaz caught at long-on. Chameera then sealed the game by hitting the right lengths.

Earlier, after being asked to bat first, Mishara and Kusal Mendis (40) gave Sri Lanka a breezy start of 58-1 inside the first six overs after Salman Mirza had Pathum Nissanka (8) bowled in the third over.

Mendis smashed six boundaries and a six before he was undone by Abrar Ahmed's quicker delivery that skidded into him and had him trapped plumb leg before wicket.

But Mishara kept scoring at a good pace as he swept well in front of the wicket before he eventually perished in the 17th over when he holed out at deep mid-wicket.

Janith Liyanage (24 not out) and captain Shanaka (17 not out) then smashed 24 runs of the final two overs of Mirza and Mohammad Wasim which proved enough for Sri Lanka to defend.

"I think it was gettable with the dew coming in but we lost too many wickets in the powerplay and gave away too many runs in the powerplay," Agha said. "If you give too many runs in the powerplay, you'll always be chasing the game. I would have been happier if I had finished the game but it was good to spend some time out in the middle."

(With AP Inputs)