In an electrifying Champions League performance, Arsenal striker Danny Welbeck scored a hat trick that even surprised manager Arsene Wenger.

If he keeps up the form from Wednesday's win over Galatasaray, the $27 million Wenger spent to bring Welbeck from the Manchester United bench to the Arsenal front line could prove to be one of the bargains of the year.

"It is good that slowly he gains confidence and finishes well," Wenger said after the 4-1 win over Galatasaray. "Hopefully the hat trick will help him gain confidence. It is not just his finishing because he wants to help the team. His team play is good as well, his teamwork and work-rate. I believe that, technically, he is very sound, a good passer of the ball."

Welbeck can show the treble wasn't a one-off when Arsenal travels across London with its notoriously porous defense to play Chelsea. Yet, Chelsea's new striker has even eclipsed the instant impact Welbeck has made. Diego Costa, who joined from Atletico Madrid for around $53 million, has scored eight goals in six league games - even with left thigh problems - to ensure Chelsea tops the fledgling standings.

"We've seen it before, some strikers take months and months, but he's hit the ground running," Chelsea captain John Terry said. "Without speaking a word of English he gets by and gets on great with everyone. He puts himself about but gets up and battles on, and plays with little niggles."

Chelsea is six points ahead of Arsenal, which is in its familiar position of fourth.

Here's a look at the pick of the other Premier League games this weekend:

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LACKLUSTER LIVERPOOL

With just two wins from six league games, life at Liverpool without Luis Suarez continues to be a struggle. And Daniel Sturridge could still be sidelined on Saturday when last season's runners-up host West Bromwich Albion. Europe has provided no respite either, with Brendan Rodgers' team losing 1-0 at Basel on Wednesday in the Champions League.

"I thought we were too soft all over the pitch," captain Steven Gerrard said in Switzerland. "I thought they wanted it more, which is very disappointing. Conceding again from a set-piece isn't good enough, so we need to get it right."

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POCHETTINO'S PROBLEMS

When Mauricio Pochettino switched from Southampton to Tottenham, this wasn't how he envisaged the start to the season. Tottenham, having opened the league campaign with two wins, has now gone four matches without a victory.

Southampton, despite an exodus of star players, has not imploded as bookmakers predicted with their relegation odds, but is sitting second in the league. Ronald Koeman's side has won four of its opening six league fixtures heading into Sunday's match at Pochettino's Tottenham.

One of Pochettino's problems is striker Emmanuel Adebayor only scoring once in the league.

"We know always a striker maybe during some periods finds it difficult to score, but he made a lot of effort for the team," Pochettino said.

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ELSEWHERE...

Alan Pardew seems to be the Premier League manager under the greatest pressure, with Newcastle playing Swansea on Saturday with just three points and second from bottom.

Manchester United hosts Everton on Sunday with a chance to win back-to-back matches for the first time under Louis van Gaal this season. Captain Wayne Rooney begins a three-match suspension after being sent off in last weekend's 2-1 win over West Ham.

Third-place Manchester City travels to Aston Villa on Saturday, which is just a point behind the champions, after another frustrating Champions League night. A draw with Roma on Tuesday left City with just one point from two group stage matches.

Also Saturday, newcomers Leicester and Burnley meet, Sunderland plays Stoke, and Hull hosts Crystal Palace. There's another London derby on Sunday with West Ham hosting Queens Park Rangers.