Celtic's display in strengthened manager Neil Lennon's belief that they can compete in their difficult Champions League group.
"It is a step up, but the players have the experience of last year," said Lennon, whose side travel to Italy to face AC Milan on Wednesday.
"They are international players, so it won't faze them.
"The way we're playing and the confidence in the squad, I think we can surprise a few people again."
Celtic reached the last 16 in last season's Champions League, recording a famous win over Barcelona in Glasgow during the group stage.
The Spaniards are again in Celtic's group, along with Ajax, but Lennon is still targeting a first or second-place finish in the group.
"I would not say we're massive underdogs," he insisted, stressing that some of his players "have played at this level for a long time".
"We looked powerful today, as you'd expect against a young team, but we were very professional as well," said the manager.
"I thought our reaction to the Hearts goal was excellent - a great response.
"Just a little more care with the final ball and the finish, we would have won more comprehensively."
Adam Matthews was taken off shortly before half-time following a strong challenge, but Lennon expected the versatile defender to be available for Milan.
"It looked like a jolt, a twisted ankle, but the physio is saying he's hopeful he'll be okay for Wednesday," said the manager.
Anthony Stokes won Celtic the penalty from which Kris Commons opened the scoring, added the second himself following Hearts' equaliser and set up Teemu Pukki for the third.
"He took his goal brilliantly, but his overall play is getting better and it was a wonderful bit of skill for the third goal," said the manager.
"I don't know how he did it and I'm sure Teemu was delighted to see that."