But one player has not quite given up on this season's tournament.
Adam Matthews was on duty yesterday at St Anne's Primary school in the East End of Glasgow as pupils and Freddie Cowan, guitarist with The Vaccines, released Let The Games Begin, a charity single that seeks to raise money for UNICEF in an initiative supported by the Celtic Foundation. The Commonwealth Games, of course, is the subject matter for the song but the Celtic full-back has his eye on an event that precedes both the multi-nation gathering in Glasgow and the Champions League qualifiers that await his side in July.
Matters in Munich on Tuesday night have focused Matthews' eyes on the Champions League final in Lisbon on May 24.
"I'm really hoping that Gareth [Bale] can go on and win his first Champions League. Not just for him, but for Welsh football, in general," Matthews said of his countryman after Real Madrid's demolition of Bayern Munich with a 5-0 aggregate semi-final victory. "I haven't asked him for tickets yet, but I think that text message might be on the way shortly," said the 22-year-old.
Matthews might just have been reflecting on bitter experience when he said: "Real Madrid showed in the semi-final how good they are going forward. Bayern had more possession, but Real were just too quick on the counter-attack."
He is aware that Celtic struggled in the Champions League against fast-breaking sides with high levels of technique. AC Milan, Ajax and Barcelona scored 14 goals in total against Celtic but Matthews is looking forward to a more productive campaign next season.
First, of course, they have to negotiate the qualifying phase and this was only successfully completed with a very late goal by James Forrest against Shahkter Karagandy this season.
"Do we get harshly dealt with? Maybe so," said Matthews of the Scottish champions potential long haul to the group stages.
"The start of last season was really tough as we had a lot of games before we even kicked a ball in the Scottish Premiership," he said. However, he is relishing the prospect of having another tilt at a competition where Celtic reached the knockout stages last season.
"We would not want to be anywhere else, so it's about focus and getting the job done," he said.
Matthews is an important player for Celtic in Europe because he can not only play at full-back but as a wide man. His pace gives even the best defences problems with a conspicuously prominent display against AC Milan at the San Siro hinting at what might be to come for the young Welshman.
However, as Celtic's Champions League campaign crumbled, Matthews found his season was similarly about to be reduced to ruins. A hamstring injury curtailed his start to the season but the main damage was done in October.
He landed awkwardly after a tackle by Motherwell's Keith Lasley and was out for two months. A calf injury and a virus have further restricted his appearances.
"It's been my worst-ever season with injuries," he said of a campaign of 29 appearances. "The injury I had the season before last didn't help my hamstring. I came into this season still injured and it took me a while to get going. Then I had the shoulder problem. It's been a bad season on that front, but I've still played a part and the team has done well, which is the main thing," he said.
He now is determined to have a run of games before the Champions League qualifiers. "We'll have a little break, but the fitness guys at the club will give us a programme to work on within two weeks of going off. I want to go into the season fresh and ready."
Matthews, of course, faces competition for his place at right-back from Mikael Lustig, also back from injury and Darnell Fisher, the 20-year-old Englishman.
"Obviously, it was a bad injury with a double hip operation," he said of the Swede's absence. "But he's been doing well and it will be interesting to see who plays the remainder of the games."
Lustig is already in talks with Celtic about extending his contract and Matthews is in no rush to leave the club either. "I've got two years on my contract and I'm happy here," he said. However, Celtic have options at full-back and English clubs have been monitoring the progress of the player who came to Glasgow in 2011 under freedom of contract and now can be rated at £2m-plus.
The move to the Barclays Premier League from Celtic has already been made by one Welshman this season. Joe Ledley left in the January transfer window and has been an integral part of a resurgence at Crystal Palace that has taken Tony Pulis's side to safety.
"Joe showed for us in the Champions League how good he is and we knew he would do well in England's top-flight if he went there," said Matthews.
However, with one Welsh mate established in England's top flight and another preparing for Europe's biggest game, Matthews has another leading player to focus on. "We play Holland at the beginning of June," he said. "The squad hasn't been announced yet, but I hope to be in it. Then I can test my fitness by chasing Arjen Robben around." He might just ask Bale for a word of advice when he is on about that ticket.