NEW DELHI: Sri Lanka finally opened their account in the T20 tri-series with a commanding nine-wicket win over Zimbabwe on Tuesday, driven by a sensational unbeaten 98 off 58 balls from Pathum Nissanka.

On a surface where Zimbabwe's batters found fluency hard to come by in their total of 146/5, Nissanka was in complete control. He smashed 11 fours and four sixes, guiding Sri Lanka to 148/1 with more than three overs left.

Pakistan have already sealed their place in Saturday's final with three consecutive victories. For Sri Lanka, the equation is simple: they must defeat the hosts on Thursday. Any slip-up will send Zimbabwe through on net run rate.

Nissanka found solid support from Kusal Mendis, who remained unbeaten on 25, as the pair stitched together an unbroken 89-run partnership off 64 deliveries, leaving Zimbabwe's bowlers out of answers.

"From the start, the confidence was there," Sri Lanka captain Dasun Shanaka said. "We bowled in the right areas, especially Maheesh Theekshana... and we carried through."

Nissanka took on the fast bowlers with authority but dialled back his tempo against Sikandar Raza's spin (0-17), carefully navigating the middle overs.

He powered Sri Lanka to a rapid 59-run start in the powerplay before Kamil Mishara fell for 12, courtesy of a superb tumbling catch at mid-wicket by Wellington Masakadza.

Raza slowed the pace for a while with his four tidy overs before Nissanka cut lose against the pace and raised his half-century off 38 balls.

Zimbabwe's premier fast bowler Richard Ngarava conceded 44 runs off his 3.2 overs as Nissanka smashed three sixes against him. Fast bowler Brad Evans conceded 36 for the wicket of Mishara while third seamer Tinotenda Maposa was expensive in the power play and conceded 29 off his two overs.

Earlier, Theekshana took 2-23 when he clean bowled Tadiwanashe Marumani (4) and Dion Myers (6) cheaply inside the batting power play.

Brendan Taylor (14) twice successfully overturned on-field lbw decisions against him through reviews but couldn't last long as he tried a ramp shot against Dasun Shanka and was clean bowled round his legs.

Zimbabwe further got strangled against the spin of Wanindu Hasaranga (2-23) in the middle overs with Brian Bennett getting dismissed in a bizarre fashion.

Bennett made 34 off 26 balls, but couldn't force the acceleration before he got out hit wicket when he went too deep into his crease against Hasaranga's quicker delivery and instead of hitting the ball, the right-handed batter smashed his bat onto the stumps.

Captain Raza made 37 off 29 balls, but perished before the death overs when he sliced Hasaranga to short third in the 15th over. Ryan Burl hit five boundaries and a six to score unbeaten 37 off 26 balls, but the total proved well below-par.

"We were slightly short," Raza said. "We didn't bowl well in the powerplay, we didn't allow the ball to swing … we haven't been in a position where we have to rely on others to qualify, so it's a good position to be in. I guess everyone will be supporting Pakistan so that we can get into the final."

(With AP Inputs)