LONDON, Feb 4 (Reuters) - Arsene Wenger knows Arsenal's hopes of staying in this season's Premier League title race will be as good as over if they lose at leaders Chelsea on Sunday.Much was made of his side's crushing 3-1 home defeat by Manchester United last week being the first English match screened in 3D but Wenger needs no special glasses to see the confidence draining out of his side.Arsenal's season appeared to be coming to the boil when they went top of the table in January but a miserable 11-day period in which they lost in the FA Cup at Stoke City, drew 0-0 at Aston Villa and were then outclassed by champions United has seen it blow up in their faces.Hull City did United and Arsenal a huge favour on Tuesday by holding Chelsea to a 1-1 draw. Chelsea are still two points ahead of United, however, and six clear of third-placed Arsenal and Carlo Ancelotti will know that victory at Stamford Bridge will virtually knock Arsenal out of the equation.Arsenal have won plaudits for some of their football this season and have already scored 60 league goals but against United and Chelsea they have been second best.To their credit, they responded to a 3-0 home defeat by Chelsea in November with a hot streak that propelled them back to the top, albeit briefly, but they look fragile now and ill-equipped to win the club's first silverware for five years.Wenger normally shields his players from criticism but even he looked at a loss to explain Sunday's setback at home to United -- questioning his players mental strength."We were naive," Wenger said. "We never had any cohesion, offensively or defensively. We were completely not at our level. Why? I believe there are some mental reasons in there."Wenger was inactive in the transfer market and fans will again be questioning the manager's instincts, especially with main striker Robin van Persie out for the season and Eduardo's fitness unreliable.Easy on the eye they may be, but Arsenal cannot boast serial winners like Chelsea's Frank Lampard, John Terry and Didier Drogba or the likes of Paul Scholes, Rio Ferdinand, Wayne Rooney and Ryan Giggs at United.Chelsea scraped a win at Burnley and were disappointing at Hull in midweek, where the furore surrounding captain John Terry again overshadowed the match, but Ancelotti knows his side remain in pole position and clearly regards United as their serious rivals for the championship."I think we are in a good position now, we are in the top, we know very well Manchester is a fantastic opponent, it will be a long race until the end of the season," he said."We need all the players in good condition and involved until the end of the season. Now every game is very important and every game can decide the future of the season."Under Ferguson United have always had a habit of hitting top form at the perfect stage of the season and their League Cup semi-final defeat of Manchester City followed by a top drawer display at Arsenal looks ominous.
United host bottom club Portsmouth on Saturday knowing victory will put them top before Chelsea face Arsenal."We just want to keep winning, to put Chelsea under pressure," United's South Korean midfielder Park ji-Sung, who scored against Arsenal, told the club's website (www.manutd.com).
There's still a long time to go in the league, three months, so we just have to concentrate on our own performances. We can deal with the pressure. We'll see whether they can."
Underneath the title race, the battle for fourth spot continues with Tottenham Hotspur, who are still clinging on to it despite throwing away points with abandon, at home to one of their main rivals Aston Villa.
Manchester City, who are just a point behind Spurs with two games in hand, travel to Hull City while fifth-placed Liverpool aim to continue an encouraging league run in the Merseyside derby against rapidly improving Everton.