At McDiarmid Park on Saturday Neil Lennon's side suffered the worst possible result ahead of their opening Group G.
But Hartley reckons the Hoops players will be able to put that embarrassing 2-1 loss out of their minds at Parkhead tomorrow night.
The Alloa manager knows exactly what is required to succeed at the highest level in Europe.
He played on the last occasion the Glasgow club reached the Champions League knockout stages back in 2008 when Gordon Strachan was in charge.
And he is adamant Lennon's team can, despite their poor performance in Perth, open their European campaign with a victory against the Portuguese giants.
He said: "Sure Celtic are coming off the back of a bad result against St Johnstone.
"But they will forget about that and make sure they're ready.
"It will be an important game for Celtic. If you can manage to have a strong home performance then hopefully it will stand you in good stead.
"It's a difficult group. There are quality teams there, but Celtic are in there on merit. They've shown they can go away from home now and win in Europe."
Hartley added: "It will be a great atmosphere. Champions League nights are always special and I'm sure Neil will have his team ready.
"Hopefully they can get a good result tomorrow, get on the board with a good three points and take it from there."