The grim expression on his face made it difficult to tell but Nigel Adkins is all about positivity. No one would have been surprised if he had spoken about the need to strengthen his squad in January because without reinforcements Southampton will surely be in a scrap until the final day, yet instead Adkins preached patience, insisting now is not the time to panic and that he will only buy players who would represent an improvement on what he already has. On the evidence of Southampton's miserable defeat to Sunderland, that would not be particularly hard.

Without the verve of their captain, Adam Lallana, whose knee injury is likely to keep him out over the rest of the festive period, Southampton were one-dimensional, overly reliant on the flinty Gastón Ramírez and had little to offer once Sunderland had the measure of them. The listlessness of a performance that Adkins called "uncharacteristically flat" was inexplicable and although they are above Wigan, who are 18th, on goal difference, their next two matches see them visit Fulham on Boxing Day and Stoke on Saturday. Southampton have lost six times in seven away matches this season, their only win on their travels coming at Queens Park Rangers.

"Over the years, it has been seen that in the January window some teams panic and make poor purchases," Adkins said. "There is due diligence we do here at Southampton. We have brought several players in during the summer to try to build a team capable of playing effective football. So we can score at one end and keep them out at the other. They are the areas you look to strengthen. We have got to be sensible and diligent.

"If you bring somebody in who is going to improve you, then that's obviously very positive. But you don't just do it for the sake of doing it. If we bring somebody in, it is because they are quality and they are going to improve you. We are trying to build a team. We changed several players around in the summer so we are trying to be positive."

Victory would have moved Southampton above Sunderland, who are nobody's idea of a daunting challenge at the moment. Picking up three points almost felt obligatory, yet Southampton never clicked. "We didn't quite get out of second or third gear," the club captain and goalkeeper, Kelvin Davis, said. "We showed flashes of it, got ourselves in good positions but didn't have that finishing touch."

While Adkins seems happy with his lot despite losing, Martin O'Neill wants Sunderland's board to back him in the transfer window despite a second win in three matches. "I think we've really got to be looking to try to improve our squad next month," O'Neill said.

"Once 1 February comes around, it's a long time after that until the end of the season where you're not able to change anything. We have less players than most people in the league, so we really have to look to do something if we can. I accept it's not going to be easy, but some of the fine players we have at the club probably need a bit of help."

Fine players such as Steven Fletcher, who got the only goal of the match just before half-time when Stéphane Sessègnon's miskick from Adam Johnson's cut-back allowed him to beat Davis with a typically suave finish with his left foot from 12 yards. Sunderland do not do much apart from hope that Fletcher scores and then defend but it was enough to beat Southampton.

Man of the match Carlos Cuéllar (Sunderland)