With teams eyeing a place in the play-offs as they look to eventually secure a spot in the lucrative group stage, Turkish club Fenerbahce could hand UEFA organisers a headache after they secured a crucial away goal against Salzburg.
Fenerbahce's participation in the competition is still in the balance as they were included in the draw only after their two-year European ban for match-fixing was temporarily lifted by the Court of Arbitration for Sport two weeks ago.
CAS said the final decision on Fenerbahce would be issued before August 28, one day before the draw for the Champions League group stage takes place in Monaco.
UEFA could be left with a major problem if Fenerbahce beat Salzburg, then go on to win their following qualifying round tie but subsequently lose their appeal at CAS.
On Wednesday, striker Alan fired Salzburg ahead in the 68th minute before fellow-Brazilian Cristian came on as a substitute and then scored a last-gasp equaliser by slotting in from the penalty spot five minutes into injury time.
The tie in Salzburg was one of three matches to end in a 1-1 draw on Wednesday, with APOEL Nicosia and Slovenia's Maribor settling for the same scoreline as did Ole Gunnar Solskjaer's Norwegian side Molde with Legia Warsaw.
Partizan Belgrade, the 1966 European Cup runners-up, will be hoping to make home advantage count in the second leg after they were outclassed 2-1 by Bulgarian champions Ludogorets Razgrad.
Following a goalless first half, midfielder Sasa Markovic gave Partizan the lead in the 49th minute but the Bulgarians secured the win through strikes from Marcelinho and Mihail Aleksandrov.
To compound Partizan's misery, they ended the contest with 10 men after Milos Jojic was sent off five minutes from time following a second yellow card.
A Kris Commons header gave former European champions Celtic a 1-0 win over Swedish side Elfsborg Boras.
Celtic would have been relieved to secure the win ahead of next week's trip to Sweden, especially since Neil Lennon's men know that Elfsborg are unbeaten on their artificial home pitch since September 2011.
Elfsborg striker Mohammed Bangura, who is on loan from Celtic, was greeted by a chorus of loud boos when he made his way on to the pitch and enraged the Scottish fans further after a couple of theatrical tumbles.
However, those fans were on their feet 14 minutes before the final whistle when Commons headed in at the back post.
The return legs on August 6 and 7 and the winners of the qualifiers will reach the play-off round which offers a route into the money-spinning group stage.