Anderlecht 1-0 Celtic
Celtic's Champions League aspirations were dealt a heavy blow by defeat in Brussels to 10-man Anderlecht.
Martin O'Neill's side had an advantage in personnel for 65 minutes, following the dismissal of Belgian skipper Glen De Boeck.
But Dindane Aruna struck a 72nd-minute goal for the home team in a scrappy match, played at whirlwind pace.
Both sides were committed to attack as the game raged from end to end but Celtic failed to create many good scoring chances.
Anderlecht came within inches of taking the lead in the ninth minute when Olivier Deschacht exchanged passes with Aruna and curled a shot past Celtic goalkeeper Magnus Hedman, but the ball struck the crossbar and bounced away to safety.
The home side threatened again moments later when Aruna found room behind the Celtic defence to meet a Walter Baseggio cross but his header was comfortably gathered by Hedman.
With 25 minutes gone Anderlecht were reduced to 10 men when De Boeck received his second yellow card.
The experienced centre half was booked for a scything tackle on Henrik Larsson and was then penalised for tugging at the shirt of John Hartson.
Larsson came close to finding the net with a header from an Alan Thompson corner and, soon after, Anderlecht keeper Daniel Zitka pulled off a marvellous save to block another close-range header from the Swede.
Hartson nodded in the rebound from a yard out but the Welshman was ruled offside.
Larsson was then denied a penalty when Deschacht sent him sprawling in the area.
Eight minutes before half time Chris Sutton controlled a long ball from Didier Agathe on his chest and his flashing shot on the turn whistled just over the crossbar.
Glen De Boeck was sent off in the first half
The lively Aruna cut a swathe through the Celtic defence just before the interval but a timely lunge from Stanislav Varga finally blocked the striker's path.
Five minutes into the second half Varga popped up in attack but could only bundle a Thompson cross wide of the post from just a few yards out.
On the hour Anderlecht striker Ivica Mornar was released by a long ball over the top of the Celtic defence but his attempted lob drifted wide of the target with Hedman advancing at speed.
With 18 minutes remaining, Celtic fell behind when Christian Wilhelmsson flew down the right flank and cut back for Aruna to fire past Hedman from a central position 10 yards out.
Larsson saw a tame strike saved, substitute Liam Miller dragged an effort wide and John Hartson shot straight at Zitka from a great position as Celtic threw men forward.
But Celtic could not find a way through and have now suffered defeat in all five of the away matches they have played in the Champions League.
Anderlecht: Zitka, Deschacht, De Boeck, Zewlakow, Baseggio,
Kolar (Tihinen 90), Hasi, Wilhelmsson (Hendrikx 88), Mornar,
Subs Not Used: Peersman, Vanderhaeghe, Zetterberg, Traore,
Sent Off: De Boeck (26).
Booked: De Boeck, Hendrikx.
Celtic: Hedman, McNamara (Valgaeren 46), Balde, Sutton, Varga,
Agathe, Petrov, Lennon (Miller 80), Thompson, Larsson, Hartson.
Subs Not Used: Douglas, Gray, Sylla, Maloney, Kennedy.
Booked: Petrov, Larsson.
Referee: Fritz Stuchlik (Austria).