Celtic advanced into the Champions League play-offs with a 4-1 aggregate success, guaranteeing the Scottish champions at least a place in the group stages of the Europa League following a 2-0 win at HJK Helsinki.
Goals after the break from midfielder Joe Ledley and wide-man Georgios Samaras took the Hoops through.
Midfielder Victor Wanyama was sent off in the second half with the score at 1-0 after picking up the second of two yellow cards.
Asked if it was important for him to get through against the Finnish club, the boss Neil Lennon said: "Yes I do, just for my own sanity.
"I have been agonising over this tie for a long, long time, probably since we picked up the (league) trophy in May.
"I have been in a wee bubble for the last six or seven weeks so it s big relief for myself and a big release of pressure.
"It was a really tough tie.
"The first goal was huge, if it had gone to HJK Helsinki it would have given them a massive lift but overall, on the balance of the game, we were the far superior team.
"It was a really tough tie. Psychologically for me, it is big because I haven't got through the last couple of years but we have built a good team here and they delivered tonight and answered a lot of questions.”
"I am thrilled, absolutely thrilled for the players, the backroom team, the supporters and the club," added the Northern Irishman.
"It is a step in the right direction. The players did the business and they came good and I think it was convincing.
"We weathered the storm after the break and scored two wonderful goals so I could not be more proud of the players.
"For us to play as well as that was terrific.
"We will see what the draw brings, we are not getting carried away but this will give the players a huge shot in the arm."