Mahela Jayawardene's sublime century was too much for Zimbabwe - and the Guyanese rain - as Sri Lanka set one foot in the ICC World Twenty20's Super Eight stage on Tuesday.
Jayawardene (100) batted beautifully to help Sri Lanka rack up 173-7.
Rain at Providence then interrupted Zimbabwe's reply after one over, and it never seriously threatened a revised target of 106 in 11 overs - eventually losing by 14 runs on the Duckworth-Lewis method following another downpour.
Barring a wide-margin Zimbabwe victory in the final group game against New Zealand at the same venue on Wednesday, Sri Lanka should progress alongside the Kiwis.
Jayawardene raced past his second successive 50 and surged to his maiden hundred in this format - and the second so far in this tournament, following India's Suresh Raina against South Africa on Monday - with 10 fours and four sixes from 63 balls.
The opener traded mainly in conventional cricket shots, with the odd paddle sweep or steer fine on the off-side for occasional variety.
Zimbabwe had no answer to Jayawardene but kept chipping wickets away at the other end.
Tillekeratne Dilshan has been unable to replicate his devastating batting from last year's World Twenty20 in England - and went for only two when he mistimed a drive at Elton Chigumbura's first delivery to be caught at mid-off.
Twenty20 debutant Thissara Perera contributed some big blows to a second-wicket stand of 56 in six overs, before smashing a Greg Lamb full toss almost out of the ground only to see the ball well intercepted and held by Chigumbura at long-on.
Neither Kumar Sangakkara, Dinesh Chandimal nor Angelo Mathews could get started - the latter falling to supremely well-judged catch by Craig Ervine on the deep midwicket boundary off Lamb.
But Jayawardene kept making everything look outrageously easy and duly became the fourth batsman to make a Twenty20 international hundred, before eventually being caught at long-on off Ray Price as Sri Lanka posted easily this venue's highest total of the tournament so far.
It proved plenty too, Zimbabwe starting its run chase twice - losing Hamilton Masakadza to a comic run-out - and getting only as far as 29-1 from five overs before rain had the final say and settled the issue in Sri Lanka's favour.