AC Milan's season went from bad to worse after a last-minute goal from Australian striker Scott McDonald condemned the holders to a 2-1 Champions League defeat today.
The match ended on a sour note after Milan goalkeeper Dida was hit on the face by a fan after the winning goal.
McDonald, already in a rich vein of form after hitting a hat trick against Dundee United on Sunday, scored in the 90th minute after Dida failed to fully control a shot from Gary Caldwell.
The 24-year-old striker sent the loose ball into the net with a low shot to send Celtic fans into raptures.
Milan have made a poor start to their Serie A season but their fortunes took a dramatic turn in injury time when a fan ran on to the pitch and hit Dida.
The keeper took a few steps and then collapsed and had to be carried off the pitch on a stretcher.
Kaka had earlier equalised from the spot after Stephen McManus's 62nd minute opener.
Meanwhile, Didier Drogba helped ease the recent Chelsea blues with the winner in a 2-1 victory at Valencia after David Villa had put the home side in front early on.
Joe Cole handed Chelsea an equaliser and Drogba struck on 71 minutes to settle the Group B match and boost new coach Avram Grant after a sticky period following the departure of Jose Mourinho tow weeks ago.
Last season's beaten finalists and 2005 winners Liverpool suffered a surprise 1-0 defeat at home to Marseille in Group A with Mathieu Valbuena bagging a classy goal on 77 minutes.
Goran Pandev scored a superb brace to cancel out Ruud van Nistlerooy's double in Lazio's 2-2 draw with Real Madrid and Werder Bremen looked to be cruising at home before Olympiakos stormed back to win the Group C clash 3-1.
Jermanie Jones and Kevin Kuranyi scored second half goals to hand Schalke a 2-0 win at Norway's Rosenborg while Ricardo Quaresma grabbed the winner deep into stoppage time as 2004 champions Porto won 1-0 at Besiktas.
Benfica, beaten 2-1 in Milan two weeks ago, lost 1-0 at home to Ukraine's Shakhtar Donetsk with Jadson grabbing the goal just before the interval in their Group D match.
Reuters