Manchester United will once again turn to the Champions League for solace on Wednesday when Real Sociedad visit Old Trafford in the third round of Group A matches.

United slipped up in the Premier League again at the weekend, conceding an 89th-minute equaliser in a 1-1 draw at home to Southampton that left the defending champions eight points below leaders Arsenal in eighth place.

Manager David Moyes continues to face questions about his suitability to succeed the great Alex Ferguson, but in Europe, at least, he has been spared a bumpy ride so far.

United top the group after a 4-2 win at home to Bayer Leverkusen and a 1-1 draw at Shakhtar Donetsk and approach the double-header with Real Sociedad knowing that a pair of positive results could leave them on the brink of the knockout phase.

"I feel that this is an important one for us," Moyes said.

"If we could win this one, it would give us a strong position in the group. We have to go out there and take advantage of the home game and try to get a result.

"I hope it will go to plan. That's what we want to do to put us in a strong position early on."

Real Sociedad secured their place in the continent's premier tournament with a stunning fourth-place finish in La Liga season, before eliminating French group-phase perennials Lyon in the qualifying rounds.

Their form has deserted them since, however, as they lost both their opening group matches and had gone nine games without a win in all competitions prior to Saturday's 2-1 victory at Valencia.

The Basque club can nonetheless point to the departures of both coach Philippe Montanier and star midfielder Asier Illarramendi during the close season as mitigating factors, and Moyes feels that their early-season results have not reflected their true worth.

"I think they're just getting the balance back in the team after selling their best player last season to Real Madrid," said the Scot.

"Maybe they've not started the season how they would have liked, but I know that they were unlucky to lose in the last minute against Bayer Leverkusen from a free-kick so they will be hoping to get themselves up and running.

"We have to make sure we do the job, be professional and try to take all the points in this game."

United could be without senior centre-backs Rio Ferdinand and Nemanja Vidic, as well as midfielder Tom Cleverley, all of whom missed the draw against Southampton with minor injuries.

Moyes must also decide whether or not to keep faith with 18-year-old winger Adnan Januzaj, who has started both of United's last two games and signed a new five-year contract on Saturday.

Esteban Granero and Dani Estrada remain sidelined through injury for the visitors, but captain Xabi Prieto is in contention to start after making a 15-minute cameo at Valencia following a hamstring problem.

Despite his side's recent travails, Real Sociedad manager Jagoba Arrasate says that they will take belief from their performance at the Mestalla.

"I think we will grow and hopefully this win will be the start of a positive run, because until now I don't think we got the points we deserved," said the 35-year-old, who is taking charge of a top-flight club for the first time in his career.

"Now, with the win in our locker, we can think about Manchester, where we will play a historic match. To go to this stadium makes us all very excited.

"Moreover, with this victory, we go there with confidence. When you have faith in what you are doing, you are always closer to victory."

Wednesday's match will be the first ever encounter between the sides.

Real Sociedad have only played in England once before, losing 6-0 to Liverpool in the 1975-76 UEFA Cup, but United have won just one of their last six home games against teams from Spain.