Pathum Nissanka's record-breaking double century steered Sri Lanka to a comfortable 42-run win over Afghanistan Friday in the opener of their three-match one-day international series at Pallekele.

Set a stiff target of 382, Afghanistan reached 339 for six as Mohammad Nabi and Azmatullah Omarzai scored centuries after their team were reduced to 55-5.

Nissanka's unbeaten 210 was Sri Lanka's first ODI double hundred, breaking the island nation's longstanding record highest score of 189 by Sanath Jayasuriya against India in 2000.

It was also the joint fifth-highest individual score in ODIs.

"We are absolutely thrilled with that performance," Sri Lankan seamer Pramod Madushan told reporters.

"Great to be part of the dressing room in such an historic moment.

"It was tough out there but Pathum did well to soak up all the pressure and put us on top."

Sri Lanka's 381-3 was also their biggest total at the ground and the team's fourth-highest overall.

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.

Afghanistan stumbled early in their daunting chase, with the tourists losing five wickets inside nine overs.

Madushan cut through the top order for match figures of 4-75.

Dushmantha Chameera took the other two wickets to fall but walked off the field halfway through his eighth over, appearing to be suffering from back pain.

Omarzai (149 not out) and Nabi (136) fought back aggressively with a 242-run stand for the sixth wicket, Afghanistan's second-highest for any wicket in ODIs, to briefly give Sri Lanka a fright.

Omarzai's maiden hundred came from a flicked six off pacer Janith Liyanage.

Sri Lanka's innings saw Avishka Fernando score 88 from as many deliveries before he was caught by Ibrahim Zadran at backward point in the 27th over.

Skipper Kusal Mendis was next in but failed to make an impact and fell for a 31-ball 16.

Sadeera Samarawickrama hit 44 off 36 deliveries in his 120-run partnership with Nissanka.