Sri Lanka bundled Pakistan out for a meager 122 and scored a seven-wicket victory in a group match which paved their way to win the Asia Cup back on home soil in July.
The Sri Lankans also won the Asian Test title in 2002.
"Asia Cup is finished and this is a new tournament at a new venue but it was nice to win a major event like the Asia Cup," Atapattu told reporters Tuesday.
"We need to build on that win by achieving good results here."
The tri-series event also involves a new look Zimbabwe side who have lost both their matches against Pakistan.
"There are two major sides in this tri-series and we need to beat them to qualify for the final and that's what our aim is," said Atapattu, whose side will miss the guile of wily off-spinner Muttiah Muralitharan.
"Of course, we miss Muralitharan but in the last few months we have shown good all round performances from the available players."
Muralitharan, who holds the world record of most Test wickets with 532 besides 366 one-day wickets in 237 matches, is recuperating after a shoulder injury and is not on this tour.
Atapattu said his four-pronged pace attack gives his side some edge.
"We have four pacers with the return of Dilhara Fernando so that gives us more options and we are right up there to expose any weakness Pakistan has," he said.
Fit-again Pakistan captain Inzamam-ul Haq said the Asia Cup was history.
"What happened in the past is past, we now look to do well in the first real challenge of this tournament and we are ready for that," said Inzamam, who missed Sunday's game against Zimbabwe due to groin injury.
Also back in the squad are express pacer Shoaib Akhtar and allrounder Abdul Razzaq who were both rested during Pakistan's three-wicket win over Zimbabwe on Sunday.
Pakistan will persist with Younis Khan as wicketkeeper in Wednesday's match to include one extra batsman as regular keeper Moin Khan has still to recover from flu and fever.
"We know Sri Lanka is a tough side but after two good games against Zimbabwe we are well-tuned and hope the guys raise their level and give us the one more win to qualify for the final," said Inzamam.
Inzamam admitted Muralitharan's absence would help Pakistan.
"His absence would give us advantage but having said that we know Sri Lanka have recently beaten South Africa without Muralitharan," he said.
Pakistan: Inzamam-ul Haq (capt), Yasir Hameed, Salman Butt, Shahid Afridi, Bazid Khan, Younis Khan, Shoaib Malik, Yousuf Youhana, Misbahul Haq, Abdul Razzaq, Moin Khan, Shoaib Akhtar, Mohammad Sami, Rana Naveedul Hassan, Rao Iftikhar
Sri Lanka: Marvan Atapattu (captain), Mahela Jayawardene, Sanath Jayasuriya, Kumar Sangakkara, Tillakaratne Dilshan, Saman Jayantha, Avishka Gunawardane, Chaminda Vaas, Upul Chandana, Farveez Maharoof, Nuwan Zoysa, Dilhara Fernando, Kaushal Lokuarachchi, Thilina Kandamby, Rangana Herath
Umpires: Mark Benson (ENG), Asad Rauf (PAK)
Tv umpire: Nadeem Ghauri (PAK)
ICC match referee: Jeff Crowe (NZL)