(CNN) -- Seven-time champions AC Milan took a decisive step towards qualifying for the group stages of this year's European Champions League with a 1-1 draw at PSV Eindhoven Tuesday.
The Serie A giants will go into the second leg at the San Siro with the crucial away goal after Stephan El Shaarawy put them ahead in the 15th minute as he headed home a cross by Ignazio Abate.
Mario Balotelli should have doubled the lead soon afterwards but a youthful PSV team enjoyed much of the play and deserved to equalize on the hour mark.
Christian Abbiati failed to hold a Stijn Schaars shot and Tim Matavz was on hand to score.
Andrea Poli might have given Milan a late winner, but they will be favorites to progress from the return in the San Siro next week.
Seven-time French champions Lyon will be struggling to qualifying after going down to a 2-0 home defeat in their Stade Gerland to Spanish side Real Sociedad.
Both have made excellent starts to their league campaigns, but it was the visitors who dominated the first leg of their showdown and went ahead to a superb opener from Antoine Griezmann on the volley.
The Basque side's second goal was even better as Haris Seferovic struck a blistering volley of his own home from long range.
Lyon attempted to rally but Milan Bisevac was sent off for a second yellow card to end a miserable night for the home side.
Meanwhile, Scottish champions Celtic, who reached the last 16 last year, are facing an early exit after going down to a shock 2-0 defeat in Kazakhstan to Shakhter Karagandy.
Shakhter captain Andrei Fionchenko gave his unfancied side a 12th minute lead before Celtic nearly equalized with a number of close efforts.
The best saw Kris Commons hit the woodwork, while James Forrest's was kept out by home goalkeeper Alexsandr Mokin with a desperate last ditch save.
Celtic's hopes dipped when Sergei Khizhnichenko headed past visiting keeper Fraser Forster as his side bid to become the first Kazakh side to go into the group stages draw.
In other matches Tuesday, Viktoria Plzen beat Maribor 3-1 and Zenit St. Petersburg were 4-1 winners at Pacos de Ferreira, with Roman Shirkov scoring a hat-trick for the Russians.
Wednesday sees five further qualifying matches with English Premier League Arsenal facing a tricky first leg tie in Turkey against Fenerbahce.