But as they attempt to book their place in Friday's play-off round draw and a shot at the group stages – where a cheque for around £15million awaits – Kris Commons believes all the pressure is on the Finns.
The Hoops lead 2-1 from the first leg, and the man who played a major part in both goals, and scored the winner against Aberdeen in their SPL opener last Saturday, is confident the Parkhead club will not blow their advantage.
The artificial surface and the fact Helsinki are half-way through their season are big advantages to the Finns.
But, while Commons saw enough in the first leg to know HJK pose a threat, he did not see anything to shake his belief Celtic are the better side and can send Helsinki into the Europa League play-off.
He said: "We're not going to go out and try to shut up shop. We're going to try and play our football and score some goals.I think we'll do that, we will cause them problems The pressure is all on them.
"Hopefully they will leave gaps and we can exploit that."
Commons' only disappointment from the first leg at Parkhead was that it took the Finns to open the scoring before the Hoops really found their drive.
A strike from Gary Hooper and a header from Charlie Mulgrew gave Neil Lennon's side the victory on the night, and Commons expects the Hoops to produce a longer burst of their true form tonight.
He said: "It would have been nice to keep a clean sheet and maybe get another goal.
"But the objective was to win and take a lead to the second leg, and we did that.
"Hopefully, we can reproduce that form and get another couple of goals. It was a bit of a wake up call when they scored early in the second half.
"It jumped us back into gear, and there were some good performances in the first 20 minutes of that half.
"For us to come from behind and show the kind of fighting spirit which made us champions last season was a positive."
Commons needs no reminding that HJK defeated Reykjavik 7-0 on this plastic pitch in the previous round before winning the return in Iceland 2-1.
He acknowledges they will have to be on their guard.
"Fraser Forster didn't have a great deal to do in the first leg, but they do have some danger men," he said.
"It will be a tough tie and we have to be back on our A game."
