First one-day international, Karachi:
Pakistan 220-2 (45.5 overs) bt Sri Lanka 219 (45.2 overs) by eight wickets
Butt was in great form in Karachi
An unbeaten 100 from Salman Butt helped Pakistan secure an eight-wicket victory over Sri Lanka in the first day-night contest in the three-match series.
Pakistan, playing their first home match in six months, reduced Sri Lanka to 219 with Iftikar Anjum (4-42) and Umar Gul (3-30) doing the damage.
The tourists began well but fell apart after Jehan Mubarak's removal - the last six wickets going for 49 runs.
A stand of 168 between Khurram Manzoor (83) and Butt paved the way for a win.
Butt finished unbeaten with his 100 runs coming off 117 balls while fellow opener Khurram played the patient role, striking his 83 off 128 balls.
Khurram was caught and bowled by Muttiah Muralitharan and Sri Lanka's only other success was the wicket of Younis Khan (20) who was caught by Ajantha Mendis off the bowling of Farveez Maharoof.
But by that stage the home side only needed 15 more runs for victory, a target Butt and captain Shoaib Malik ensured their side reached.
Earlier, Sri Lanka were going along well, with 71 runs on the board before Gul removed Tillakaratne Dilshan (42) with Sanath Jayasuriya following soon after (38).
Dilshan miscued a hook straight to Butt, while Jayasuriya fell leg before.
Iftikar then took centre stage by having Mahela Jayawardene caught behind by Kamran Akmal.
Kumar Sangakkara settled his side down by putting on a 54-run fourth wicket stand with Chamara Kapugedera, before he became the second victim of Iftikar.
Once Kapugedera (27) was cleaned bowled by Shahid Afridi and Mubarak (8) was run out, Sri Lanka's innings fell apart.
"Our bowlers bowled the right areas, and restricting them to 219 was pleasing," said captain Shoaib.
"We bowled the same manner in our series against the West Indies.
"We did some homework against Mendis and our planning was successful."
Sri Lanka skipper Mahela Jayawardene was disappointed with his batting.
"We couldn't capitalise on a good start and lost wickets regularly," he said.
"I think 220 wasn't enough and we need to do better on Wednesday."
Victory will undoubtedly boost the spirits of Pakistan's cricket-loving public who have had competitions cancelled because security fears in the last six months.
One of which was last September's Champions Trophy which was postponed for a year by the International Cricket Council while Pakistan played the West Indies at a neutral venue in the United Arab Emirates last November.
However, Sri Lanka accepted the Pakistan Cricket Board's offer to tour and return for two Tests in February after India cancelled its tour in the wake of the terrorist attacks in Mumbai in November.