Arsenal have been drawn to face Turkish club Fenerbahce in the Champions League play-offs.
Fenerbahce are awaiting a final ruling from the Court of Arbitration for Sport (CAS) over whether they will be allowed to go into the competition proper this season, having been banned from competing in Europe by UEFA for match-fixing in domestic competition.
They have challenged that ruling and a CAS verdict is due before the group stage draw is made, but home and away matches against Arsenal stand to go ahead before that decision arrives.
UEFA say no decision has yet been made regarding what would happen in the event of Fenerbahce winning the tie and losing their CAS appeal.
Fenerbahce finished second in the Turkish Super Lig last season, while Arsenal took fourth place in the Barclays Premier League.
Celtic have been drawn against Shakhter Karagandy of Kazakhstan in what appears a favourable draw, travel notwithstanding, for Neil Lennon's team as they bid to reach the group stages.
Former European champions PSV Eindhoven and AC Milan will meet in a mouthwatering tie.
PSV, under Phillip Cocu, have undergone some major squad reconstruction this summer with the likes of Kevin Strootman, Dries Mertens, Erik Pieters and Jeremain Lens all leaving the Philips Stadion with Park Ji-sung, Stijn Schaars, Adam Maher and Jeffrey Bruma coming in.
Real Sociedad's reward for their impressive Primera Division campaign is a two-legged tie with French giants Lyon.
The San Sebastian club finished fourth last term but have since lost coach Philippe Montanier to Rennes and key midfielder Asier Illarramendi to Real Madrid.
Schalke meet Metalist Kharkiv while Zenit St Petersburg will be confident of seeing off Pacos Ferreira.
Swiss champions Basle, semi-finalists in the Europa League last season, meet Ludogorets Razgrad, Dinamo Zagreb take on Austria Vienna, Viktoria Plzen face Maribor and Legia Warsaw were paired with Steaua Bucharest.
The Gunners are slight 6/4 favourites to win the opening leg in Istanbul later this month, but are 2/5 to complete the job at the Emirates.
Celtic too are favourites in the away leg, with the Scottish champions 2/7 to win the tie.
Arsenal's tough draw has seen their Champions League outright price drift from 22/1 to 28/1, but any English team to win this season's competition remains a 5/2 chance.
Sky Bet's Chris Spicer said: "Turkey is a notoriously difficult place to go for English teams so we're wary of Fenerbahce's threat in the first leg.
"However, we're confident Arsene Wenger will be well prepared for the tie, so we're going short at 2/5 on them to progress."