Centurions Dimuth Karunaratne and Kusal Mendis made Ireland's wayward bowlers toil on Sunday to put Sri Lanka in a commanding position on day one of the first test in Galle.
At stumps in hot and humid conditions in the sides' first test series, the hosts were 386 for four with Dinesh Chandimal unbeaten on 18 and night-watchman Prabath Jayasuriya 12 not out.
After winning the toss and opting to bat, captain Karunaratne completed his 15th test hundred before making 179 while Mendis scored 140, his eighth ton in the five-day format.
Opener Nishan Madushka was caught behind for 29 off Curtis Campher to give the Irish an early breakthrough.
But Karunaratne and Mendis added 281 runs for the second wicket, beating the previous record in Galle of 253 set by India's Shikhar Dhawan and Cheteshwar Pujara in 2017.
Still seeking their first win after securing test status in 2017, Ireland's bowling lacked penetration and there were too many short and wide balls that were duly punished.
The partnership was finally broken when Mendis missed a sweep shot off the left-arm spin of George Dockrell to be trapped leg before wicket in the final hour of play.
Former captain Angelo Mathews then fell for a three-ball duck, swinging hard at a wide delivery by legspinner Benjamin White to be caught behind.
The second new ball brought about Karunaratne's downfall as he fell with six overs left for stumps, attempting a drive off Mark Adair without much foot movement and was caught behind.
His 179 came off 235 balls with 15 boundaries.
During the knock, he became the fifth-highest run scorer for Sri Lanka in tests going past the great Aravinda de Silva with now 6 409 runs in 85 tests.
There was turn and bounce for the spinners, as is always the case in Galle, but the Irish bowlers failed to make the most of the conditions and apply enough pressure.
Sri Lanka were quick to punish the loose balls going at a brisk 4.39 runs an over as they took control of the game.
Ireland have lost all of their previous four tests, including to Bangladesh earlier this month, and this is the first time Ireland has been involved in more than one test match in a series.
Sri Lanka: Dimuth Karunaratne (captain), Nishan Madushka, Kusal Mendis, Angelo Mathews, Dinesh Chandimal, Dhananjaya de Silva, Sadeera Samarawickrama (wicketkeeper), Ramesh Mendis, Prabath Jayasuriya, Vishwa Fernando, Asitha Fernando.
Ireland: James McCollum, Murray Commins, Andy Balbirnie (captain), Harry Tector, Curtis Campher, Peter Moor, Lorcan Tucker (wicketkeeper), Andy McBrine, Mark Adair, George Dockrell, Ben White.