Bayern Munich’s Michael Ballack in an aerial duel with Emerson of Juventus during their Champions League match at the Delle Alpi Stadium in Turin on Wednesday. (AFP)

London: Barcelona and Arsenal swaggered through to the last 16 of the Champions League on Wednesday but Manchester United’s hopes hang in the balance after another demoralising defeat. United’s 0-1 defeat by Lille in Paris intensified the pressure on manager Alex Ferguson and threw group D wide open.

Cameroon striker Samuel Eto’ hit a sparkling hattrick in Barcelona’s 5-0 thrashing of Panathinaikos which assured them of qualification from group C.

Dutchman Robin van Persie scored twice as Arsenal maintained their 100 percent record in group B with a 3-0 home win over Sparta Prague but Bayern Munich’s hopes of qualifying on the night were dashed after a 1-2 loss at Juventus in group A.

On Tuesday French side Olympique Lyon and nine-time winners Real Madrid confirmed their places in the last 16.

United are in danger of not reaching the knockout phase after their defeat, combined with Villarreal’s win at Benfica, left all four teams still in contention to qualify.

Marcos Senna’s long-range effort eight minutes from time gave Villarreal, who visit Old Trafford next, a 1-0 win in Portugal and they top the group on six points, with Lille and United on five points and Benfica on four.

United arrived in Paris, where Lille are playing their home matches due to ground redevelopment, still in shock after a 4-1 weekend thrashing by Middlesbrough.

Lille profited after 38 minutes when Slovenian Milenko Acimovic raced through a hole in the centre of United’s defence and crashed the ball home to register the French team’s first goal in the Champions League this season.

In the Nou Camp Barcelona scored in the opening minute and quickly swamped their Greek opponents. Dutchman Mark van Bommel lobbed them in front and Eto’ grabbed two either side of 18-year-old Lionel Messi’s effort to make it 4-0 at halftime.

Eto’ completed his hattrick just past the hour with a beautifully curled shot and with 10 points from their four matches, the Catalan club cannot fail to finish in the top two in their group with the three other teams on four points.

One of those is German side Werder Bremen, who breathed life into their campaign with an extraordinary 4-3 home win over Udinese.

The Italians recovered from 0-3 down early in the second half to level at 3-3 with three goals in six minutes before Johan Micoud’s second of the night clinched the points for the Germans.

The David Trezeguet double earned Juventus revenge for their defeat at Bayern by the same score two weeks ago. The French striker’s goals came either side of a Sebastian Deisler goal for Bayern, lifting Juventus atop the group on nine points, the same as the Germans. (Reuters)