Neil Lennon and James Forrest led the chorus of praise for Cliftonville after the Reds produced a performance full of guts and character at Parkhead.
Tommy Breslin's men relished playing at the famous Glasgow stadium, home of the 1967 European champions, and although they couldn't find the net in the aggregate 5-0 loss the north-Belfast side frustrated the Hoops for most of Tuesday night's second leg battle.
Lennon's men were expected to cruise into the third qualifying round of the Champions League, but the anticipated avalanche of goals after the 3-0 win at Solitude failed to materialise at Paradise.
Forrest, who scored in the first leg, revealed that the post-match talk in the home dressing room centred on the magnificent effort put in by the Irish League part-timers.
"A few of the boys were saying after the game that they were very impressed with Cliftonville and they passed the ball around the park really well," said the 22-year-old Scotland international.
"We were a wee bit surprised with their performance at Parkhead, but they certainly came here and did well."
The Hoops made £22m from last season's Champions League adventure which saw them defeat Barcelona in the group stages before reaching the last 16.
Cliftonville's earnings are much more modest, but they will be still be richer to the tune of around £200,000 thanks to Uefa cash, plus TV and ticket income and the relationship between the two clubs is now stronger than ever.
Former Northern Ireland international Lennon was thrilled that Celtic kept another clean sheet in the 2-0 win, sealed by goals from Efe Ambrose and Georgios Samaras, but Cliftonville have also left a lasting impression on him.
The former Glenavon ace said: "Cliftonville set up a little differently with three in midfield and Liam Boyce up front and that surprised us a bit because Tommy has been quite consistent in his selections.
"I was surprised to see Joe Gormley left out, but they created a few chances and a goal for them would have been the icing on the cake for everyone concerned.
"They performed well and certainly didn't disgrace themselves. I still think that Liam Boyce has a future in the professional game. He just needs that full-time training to bring him along.
"There's no doubting his technical ability, but with more training he could become more mobile. He certainly knows where the goal is. I like Barry Johnston as well. He's probably getting on a little bit, but I feel four or five years ago he could have played across the water.
"The two ties have been brilliant and there's a great relationship between the clubs. I've just seen Gerard Lawlor (Cliftonville chairman), who I have known for quite a while, and this tie will leave a lot of happy memories for many people.
"While the money from this competition is important to clubs for me it's also about the careers and reputations of the players. It's about their development too.
" Now we look forward to facing Elfsborg in the knowledge that our place in the Champions League group stage can never be taken for granted."