Brendan Rodgers' first game as Celtic boss ended in a humiliating 1-0 defeat to Gibraltar's Lincoln Red Imps in the first leg of their second round Champions League qualifier on Tuesday.
Celtic laboured in the searing heat of the goalless first 45 minutes and were then stunned when Lee Casciaro, who had scored Gibraltar's first international goal against Scotland at Hampden in 2015, sensationally put the part-timers ahead in the 47th minute.
Hoops striker Leigh Griffiths hit the woodwork twice as the Scottish champions battled for their dignity, but, buoyed by their stunning breakthrough, the home side held out for a result which ranks among the more embarrassing in Celtic's European history.
The return game at Celtic Park next week should still be a formality, but Rodgers' tenure began in the worst possible way.
"We've given ourselves a bit of work to do. I saw enough from the game, we created enough to go through," Rodgers said. "Of course you never want to lose the game. You let the local team have their night, we press on, another week's training and be better for it.
"There's no embarrassment. We never took our chances and they took theirs. The second leg will be different."
Welsh club The New Saints will go into the return leg of their tie with APOEL on level terms following a goalless draw at Park Hall.
Brazilian midfielder Vinicius could have put the Cypriots ahead in the opening period but he fired over from close range.
TNS goalkeeper Paul Harrison prevented the Welsh champions falling behind ahead of next week's return match when he produced a fine save to keep out a low 25-yard effort from former Chelsea player Nuno Morais.
Belarus' BATE Borisov, who reached the group stage the past two seasons, won their home leg over SJK of Finland after goals from Yuri Kendysh and Vitali Rodionov.
Dinamo Zagreb held on to defeat Vardar 2-1 in Macedonia, Nemanja Mijuskovic and Junior Fernandes scoring away goals in the first half before Hovhannes Hambardzumyan drew one back.
Maharan Radi's stoppage time penalty carried Hapoel Beer Sheva to a 3-2 win over 10-man Sheriff Tiraspol in Israel.
The Moldovan side opened the scoring with Josip Ivancic's goal, only for Fidan Aliti to be send off four minutes later. The hosts responded with goals from John Ogu and Elyaniv Barda, but Josip Brezovec equalised before Radi's late winner.
Poland's Legia Warsaw managed a 1-1 draw at Zrinjski Mostar in Bosnia, Nemanja Nikolic's opener for the hosts cancelled out by a Matija Katanec goal eight minutes later.
Dinamo Tbilisi of Georgia defeated first-round winners Alashkert of Amenia 2-0 after Otar Kiteishvili scored in the second half and Giorgi Kvilitaia added a penalty.
Red Star Belgrade won 2-1 away from home at Valletta in Malta, Aleksandar Katai and Predrag Sikimic scoring to erase Federico Falcone's 15th-minute goal for the hosts.
Jonathan Soriano scored seven minutes from time to give Red Bull Salzburg a 1-0 win over Latvia's Liepaja.
Azerbaijan's Qarabag won 2-0 at home over Luxembourg's F91 Dudelange thanks to a first-half Richard Almeida brace.