Chelsea and Arsenal both had to settle for a point on Matchday Four, meaning they still have work to do to reach the knockout stage.
Blues and Gunners held as Barca book their place in the last 16
Chelsea and Arsenal both had to settle for a point on Matchday Four, meaning they still have work to do to reach the knockout stage of this season's UEFA Champions League.
The Blues were left to rue missed opportunities on the road, while the Gunners failed to trouble the scorers on home soil.
Chelsea boss Andre Villas-Boas was looking for a positive response from his side following their 5-3 derby defeat to Arsenal on Saturday, but was posed further questions in a 1-1 stalemate with
Genk.
The Blues hammered their Belgian opponents 5-0 in their last European outing, but found the going a lot tougher away from home.
Ramires was the only man to find the target on this occasion, with the Brazilian combining well with Fernando Torres on 25 minutes before drilling across goal and into the corner of the net.
Raul Meireles then hit the bar for the visitors, before David Luiz spurned a golden opportunity to double their lead.
Thomas Buffel was adjudged to have deliberately handled a Florent Malouda cross inside the box, but Luiz saw his spot kick saved by Laszlo Koteles.
He was made to pay for that mistake on 61 minutes when Fabien Camus' inviting cross was turned in by Jelle Vossen.
Chelsea are only three points clear of third-placed
Valencia with two games to go after the Spaniards saw off
Bayer Leverkusen 3-1.
Los Che took the lead inside 12 seconds as Oliveira Jonas returned the ball with interest following a terrible clearance by Bernd Leno, but Leverkusen levelled on 31 minutes when Michael Ballack, sporting a face mask to protest his broken nose, crossed for Stefan Kiessling to head home.
The hosts, aware that they desperately needed to win to keep their European dream alive, grabbed a second on 65 minutes when Roberto Soldado expertly flicked the ball past Leno and they put Leverkusen out of sight 15 minutes from time when Adil Rami nodded in from a corner.
Uninspiring
There was to be no repeat of the late drama which saw
Arsenal snatch three points off
Marseille last time out when the two teams were reacquainted at the Emirates, with a goalless draw a fair reflection on an even contest.
Didier Deschamps had vowed to attack the Gunners prior to kick-off and it was the French side that made most of the early running, with Loic Remy causing plenty of problems.
Arsene Wenger's men came into the game as the first half wore on but, despite knocking on the door, they were unable to unlock Marseille's dogged defence.
With the scores level the visitors were never out of the game and they gave Arsenal a few nervy moments before the curtain came down on an uninspiring encounter.
Borussia Dortmund picked up their first victory in Group F as they saw off notoriously poor travellers
Olympiakos 1-0 to clamber above the Greek outfit into third place.
A 25-yard thunderbolt from Kevin Grosskreutz won the game for the reigning German champions, with his seventh-minute effort leaving Balazs Megyeri flapping at thin air.
Qualification
Barcelona find themselves in the enviable position of being able to take their foot off the gas with two games to spare after they saw off
Viktoria Plzen 4-0 to book their place in the knockout stage.
The prolific Lionel Messi was at it again for the current European champions as he netted his second hat-trick in the space of four days.
First he picked himself up off the deck to roll in a 24th-minute penalty, after Marian Cisovski had seen red for the foul, and he doubled Barca's lead in first-half stoppage time when he found the back of the net despite slipping as he shot.
Cesc Fabregas netted a third for Pep Guardiola's men on 72 minutes when he ghosted in unmarked to power home a header from six yards and Messi put the seal on a comfortable night's work in time added on.
AC Milan have joined Group H rivals Barca in the next stage despite being surprisingly held in Belarus by
BATE Borisov.
Zlatan Ibrahimovic had the Italian giants in front inside 22 minutes after finding himself in acres of space to sweep home a Robinho centre.
BATE refused to roll over, though, and their efforts in the second half were rewarded when Ignazio Abate bundled over Artem Kontsevoy and Renan Bressan made no mistake from the spot.
This season's surprise package
Apoel edged a step closer to the knockout stages with a dramatic 2-1 victory over
Porto.
Ailton's penalty three minutes before the interval broke the deadlock in Cyprus and Hulk thought he had snatched a share of the spoils when he converted an 89th-minute penalty.
There was, however, still time for the hosts to race up the other end and cross for Gustavo Manduca to produce a composed finish in the dying seconds.
Zenit St Petersburg are favourites to join Apoel in extending their continental adventure following a narrow win over Shakhtar Donetsk.
The hosts bossed their meeting in chilly Russia but only found the target only once, with Nicolas Lombaerts thumping header moments before half-time enough to see them to a well-earned victory.
