Manchester United may be unbeaten in the Premier League so far this season but Southampton are confident of securing an FA Cup upset this weekend, according to the south coast side's talisman Rickie Lambert.
United's imperious record has not always been reflected in their performances this season, with Sir Alex Ferguson's men not getting into top gear on many occasions in the current campaign.
The Saints, meanwhile, have recovered from an uncomfortable start to the campaign with aplomb under Nigel Adkins, who replaced Alan Pardew as manager in September.
Such has been the upturn in fortunes at St Mary's that the team is pushing hard for the npower League One title, leading striker Lambert to tip an unlikely victory for his side on Saturday evening.
"They haven't got many weaknesses as you can see by the fact they haven't been beaten this season," he told Press Association Sport.
"It doesn't mean it is impossible, though.
"Obviously we've got to hope that they are not firing on all cylinders when they come to our place and we are. If that happens then I think we can do it."
Southampton progressed to the fourth round thanks to comfortable victories over Shrewsbury and Cheltenham before defeating Barclays Premier League outfit Blackpool earlier this month.
Manchester United, meanwhile, were third-round winners against Liverpool, the side Lambert has followed since he was a boy.
The 28-year-old admits he was disappointed to be denied the chance of pitting his wits against the Reds and swapping shirts with their captain Steven Gerrard.
However, Lambert is hoping to succeed where Gerrard and Liverpool failed.
"The rivalry with United is something I've grown up with, so it will be an extra bit special if we beat them," said Lambert, who has numerous friends and family coming down for the game.
"Of course I am excited. I am obviously a Liverpool fan so I was a bit disappointed that Liverpool lost because we would have played them.
"But to get Manchester United is a brilliant, brilliant tie and at home as well.
"I would have loved to play at Old Trafford but to play them at home means we've got more chance of beating them."
Southampton come into the match off the back of a goalless draw with Notts County and a 2-0 defeat at Tranmere, while United have secured two victories in four days.
Having comprehensively thrashed Birmingham 5-0 at Old Trafford, Ferguson's side then overcame a two-goal deficit to secure a 3-2 victory at Blackpool on Tuesday.
Despite the two sides' differing form heading into the tie, Lambert maintains that Saints can usurp the Premier League leaders.
"Of course Saints can win it. It's a football game," he added. "I think if it was at their ground it would be very unlikely but we've definitely got a small chance of beating them at ours."
Lambert is confident that an impressive performance against United can help aid Southampton's on-field progress and prove a catalyst in their promotion tilt.
"I'm very, very happy with the progress made this season," he said.
"Obviously it wasn't the best of starts - I'm not going to go into too much detail about what happened - but obviously with the team we had it was very frustrating that we weren't doing as well as we could.
"It was nice that we finally got a manager in and since he has come in I think we have steadily picked it up and we're now showing everyone how good we are. I think we're only going to get better as well."