LONDON - Another Lionel Messi hat-trick lit up the Champions League yet again as Barcelona and AC Milan qualified for the last 16 with time to spare on Tuesday although it is APOEL Nicosia who are fast becoming the talk of the group stages.

Premier League sides Chelsea and Arsenal still have work to do to reach the knockout phase after draws against Racing Genk and Olympique Marseille respectively when victories could have sealed their passage out of their groups.

Unstoppable Argentine Messi gave Barcelona the lead with his 200th goal for the club and his 201st and 202nd followed as they beat 10-man Viktoria Plzen 4-0 in Prague to move top of Group H above Milan who were held 1-1 at BATE Borisov.

Zlatan Ibrahimovic was on target for Milan and, although the Serie A side conceded a second-half goal from the penalty spot, Barca's result ensured the two giants of European football will be in the knockout rounds come February.

Unfancied Cypriots APOEL are just one win away from joining them as winners of Group G after a last-gasp 2-1 victory against former European champions Porto.

Still undefeated, they have eight points, one more than Russian champions Zenit St Petersburg who beat Shakhtar Donetsk 1-0. APOEL visit Zenit in the next round of matches in three weeks when victory will seal an unlikely top spot in the group.

"My wish is that my players will keep playing with the same passion in the remaining two matches. If we do it, and is up to us, then we have chances for many things," said APOEL'S coach Ivan Jovanovic, whose side were given little chance to survive when the draw was made.

Ailton gave APOEL, playing in the group stage for only the second time, the lead but an 89th-minute penalty by Porto's Hulk silenced the stadium. In a barnstorming finish, Gustavo Manduca then drilled in a stoppage-time winner to spark wild celebrations amongst the home supporters.

Arsenal, whose season has recovered after a terrible start, left prolific Dutch striker Robin van Persie among the substitutes and his 30 minute cameo failed to prevent them from labouring to a 0-0 draw against Marseille in Group F.

A home victory would have put Arsenal through but a draw means both teams should still qualify. Borussia Dortmund kept alive their hopes of a top two place with a 1-0 home victory against Greek side Olympiakos Piraeus.

"We wanted to qualify tonight, but we were not at our sharpest," Arsenal manager Arsene Wenger said.

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Kill the game

Chelsea's woes continued after back-to-back Premier League defeats and accusations that captain John Terry racially abused Queen's Park Rangers defender Anton Ferdinand.

Victory in Genk looked a formality when Ramires gave them the lead but a missed penalty by David Luiz gave the Belgium club hope and Jelle Vossen equalised after the break to give his side their second point in the group.

Chelsea began the night eyeing a win which could have sealed their progress to the last 16, depending on other results, but things look less secure now for the London club who have eight points, two in front of Bayer Leverkusen who lost 3-1 in Valencia.

Brazilian Jonas scored after 12 seconds for Valencia, the second quickest goal in the Champions League.

Leverkusen host Chelsea in the next round of group matches. "We could have put the game beyond their reach. We had chances to kill the game off," keeper Petr Cech told Sky Sports. "I don't think there was a hangover (from Saturday's 5-3 home defeat by Arsenal). We now have to qualify the hard way."

Barca have no such worries.

Not only did Messi complete a double century of goals for the Spanish side, but keeper Victor Valdez set a club record for not conceding a goal - bettering Miguel Reina's 824-minute shutout run achieved in the 1972-73 season.

Messi, who also scored a hat-trick in La Liga against Mallorca on Saturday, scored a penalty after 24 minutes, fired in a second from close range just before halftime and completed his hat-trick in stoppage time.

Plzen had to play three quarters of the match with 10 men as Marian Cisovsky was dismissed for the foul on Messi which led to the penalty.

"I am happy for the match, the result and the goals, " Messi told Spanish television. "Given the result of the Milan game it was important to win. (Plzen) are not as well known as some clubs but it's not easy to come here."