Pathum Nissanka became the first Sri Lankan to score an ODI double century, powering the hosts to an immense 381 against Afghanistan at Pallekele in their series opener on Friday.
The opener finished unbeaten on 210 to break the island nation's longstanding record of 189 by Sanath Jayasuriya against India in 2000.
It was also the joint fifth-highest individual score in ODIs.
Sri Lanka's 381-3 was also their highest at the ground and the team's fourth-highest on record.
The unstoppable Nissanka's knock included 20 fours and eight sixes from the 139 balls he faced in his first ODI since the World Cup.
Avishka Fernando was dismissed for 88 after he was caught by Ibrahim Zadran at backward point in the 27th over.
Skipper Kusal Mendis took the crease next but failed to make an impact and fell for 16.
Sadeera Samarawickrama smashed 44 off 36 deliveries in his 120-run partnership with Nissanka.
Fareed Ahmad claimed the wickets of Samarawickrama and Fernando to be the pick of the bowlers with 2-79.