Paris (AFP) - A late goal by Brazilian forward Tavares gave Maribor a 1-0 win in Glasgow on Tuesday as the Slovenians progressed to the Champions League group stage and dumped Celtic out.
The Scottish champions were only in this tie after an administrative error saw Legia Warsaw's convincing win against Ronny Deila's side in the third qualifying round overturned.
But rather than seize their second chance with both hands, Celtic proved that they did not belong among Europe's elite despite coming away from Slovenia with a 1-1 draw in last week's first leg.
They were made to pay in the 75th minute when a wicked cross from the visitors' left was not dealt with and Tavares -- a prolific goal-scorer over the last six years with Maribor -- pounced to send a looping shot over the despairing dive of Craig Gordon and into the net.
Virgil van Dijk had the chance to force extra time at the death, but Jasmin Handanovic made an excellent save after the Dutchman had chested down a cross from the right and volleyed goalward from eight yards.
- Loud chorus of boos -
Maribor, who came through two previous qualifying rounds to reach this stage, can now look forward to appearing in the group stage for the first time, while Celtic must make do with the Europa League, which will come as little consolation to their fans, who greeted the full-time whistle in Glasgow's East End with a loud chorus of boos.
Deila admitted his side didn't deserve to go through.
"I think the first half was not good enough. There was too little energy and aggression," the Norwegian said.
"In the second half we went out a lot more aggressive and it was more even but they were more effective than us. In the end we haven't been good enough and that's what we have to work on."
Elsewhere, two-time European champions FC Porto are through to the group stage after outclassing French side Lille for the second time in seven days, winning 2-0 at the Estadio do Dragao in northern Portugal to go through 3-0 on aggregate.
A superb free-kick by French-born Algerian international winger Yacine Brahimi gave Porto the lead four minutes into the second half, and he then set up Colombian striker Jackson Martinez to make it 2-0 on the night.
Brahimi, who impressed at the World Cup finals scoring in Algeria's 4-2 win over South Korea as the 'Desert Foxes' reached the second round for the first time in their history, said it was an important victory.
"The Champions League counts a lot to us," said the 24-year-old.
"As a team this was an outstanding performance and we hope this is a sign of things to come."
Andre Villas-Boas's Zenit St Petersburg eased into the group stage for the fourth season running with a 3-0 win at home to Belgians Standard Liege securing a 4-0 triumph on aggregate.
Last season's Russian Premier League runners-up had been in control of the tie after winning 1-0 in Liege last week thanks to Oleg Shatov's early goal, and in the return at the Petrovski Stadium they took the lead half an hour in through Venezuelan striker Jose Salomon Rondon.
Viktor Fayzulin was sent off for two first-half bookings, but Brazilian forward Hulk added a brace after the restart, with one goal coming from the penalty spot, before Standard had Ricardo Faty sent off late on.
Meanwhile, BATE Borisov of Belarus will appear in the group stage for the fourth time after outclassing Slovan Bratislava 3-0 on the night to win 4-1 on aggregate, with Mikhail Gordeychuk, Sergei Krivets and Vitali Rodionov all scoring.
And APOEL of Cyprus, quarter-finalists in 2012, beat Aalborg of Denmark 4-0 for a 5-1 aggregate triumph, with Vinicius, Tomas De Vincenti, Stathis Aloneftis and former Celtic striker Cillian Sheridan on target.
The remaining five play-off second-leg ties will be played on Wednesday, including Arsenal at home to Besiktas after a 0-0 draw in Turkey last week and Athletic Bilbao hosting Napoli after a 1-1 draw in Italy in the first leg. The draw for the group stage will take place in Monaco on Thursday.