Ahead of the game the hosts' Head Coach, John Bracewell, gave a nod to John Anderson after his scintillating start to the season at domestic level and also handed an International debut to bowler, Barry McCarthy.
Skipper, William Porterfield asked the visitors to have a bat on winning the toss, but Ireland were unable to split openers Kusal Perera and Danushka Gunathilaka early on until skipper William Porterfield brought McCarthy into the attack to replace Boyd Rankin.
The Durham man had Gunathilaka caught by Paul Stirling at slip from just his second delivery and then followed that up a couple of overs later by deceiving Perera (32) with a slower one that the batsman sent straight back to him.
An 82-run stand between Chandimal and Kusal Mendis got Sri Lanka back on track- Mendis making 51 (7 fours) before being caught and bowled by Kevin O'Brien.
Barry McCarthy
Skipper Angelo Matthews joined Chandimal at that point and Ireland's bowlers continued to toil as this pair added another 88 before Matthews fell to Max Sorensen for 49.
New man Shanaka introduced himself by plundering 26 off Sorensen's next as the visitors upped the ante in the closing overs; however his 19-ball 42 was ended by a Rankin yorker.
The same bowler accounted for Seekkuge Prasanna a couple of balls later but Chandimal was proving much more resilient; going to his unbeaten century just two balls from the end.
Barry McCarthy celebrates
The final total was 303 for 7 as Ireland managed to stay competitive late on- Rankin (2-45) and McCarthy (2-69) the pick of the home bowlers.
The reply started well with Porterfield and Stirling putting on 53 before the latter was dismissed by Shanaka for 27 (4 fours). The same bowler accounted for both Ed Joyce (9) and then Anderson (7), however the skipper continued to stand firm.
A 68-run partnership between him and Kevin O'Brien got Ireland up to 159 but with the rain around and the asking rate climbing, Porterfield mistimed a drive and was caught by Perera off Shaminda Eranga for 72 (7 fours).
Kevin O'Brien on his way to 41 not out before the rain break
Weather sent the teams off soon after and when they returned the target was 293 in 47- a tall order of 129 runs in little more than 14 overs.
That meant Ireland needed to pick up the pace and although O'Brien went past 50 soon after the re-start, Shanaka claimed his 4th wicket as he bowled Stuart Poynter for 20.
Gary Wilson was trapped lbw by Matthews before O'Brien's fine effort ended in similar fashion to Pradeep- the all-rounder's 64 (6 fours, 3 sixes) not quite enough to dig his team out of trouble.
Shanaka (5-43) was on the mark one more time as Ireland fell away to be eventually all out for 218, leaving Porterfield with it all to do to level the series on Saturday.