"We haven't played too well in the recent past. Credit to the Afghan batters, they put us under lots of pressure. We played really good cricket in the practice games, the attitude was superb.
No matter who you play, you have to be positive. We aren't looking too far ahead, if we click we can do anything," said Mathews after Sri Lanka secured a six wicket win over Afghanistan.
Sri Lanka suffered three straight losses in Asia Cup before losing their two warm up matches against New Zealand and Pakistan in the run up to their tournament opener.
Opener Tillakaratne Dilshan roared back to form and guided his team home with an unbeaten 83 off 56 balls. Dilshan was out for a duck in the two warm up games.
"Two games I had two ducks, but I needed runs going into the big games. I'm really happy that i finished the game. 150 is a good total, this wicket is slow. Later a little dew helped.
They had some quality bowlers but we managed very well in the middle. Come to these kinds of tournaments, first match is very important that I get some runs. Senior guys need to stand up and do it for the team. The middle order can bat around us," said Dilshan.
Afghanistan captain Asghar Stanikzai said Dilshan took the game away from them.
"The total was good, not bad but Dilshan played really well. He took responsibility and played well. When you play big teams, our fielding wasn't good. We'll trey our best. Thanks to our president and parliament members for their support."