There is a longheld theory that the boss who collects the monthly accolade slips to defeat in the next game but Saints returned to winning ways with their biggest ever Barclays Premier League win as Graziano Pelle scored twice to seal a memorable week on a personal level. A goal in either half saw Pelle move onto six Barclays Premier League goals for the season and add to his match-winning Italy debut and player of the month award. Press Association The former Feyenoord striker would have been proud of Santiago Vergini’s own goal, which opened the floodgates as Southampton inflicted a damaging defeat on Gus Poyet’s side. Sunderland had started the game brightly as they looked to build on their maiden league win against Stoke before the international break but Vergini scored a clinical own goal from the edge of his box to set Southampton on their way to a stunning victory. Pelle then scored with a tap-in with Jack Cork, brought into midfield in place of Victor Wanyama, killing the game off before the break. Sunderland then shipped four goals in 16 second-half minutes as a another own goal, courtesy of Liam Bridcutt, was added to by Pelle’s second and efforts from Dusan Tadic and Wanyama. Sadio Mane had been rested following international exertions but came on to add the eighth late on, leaving some Sunderland fans in tears. Saints may boast the player of the month in Italian striker Pelle but they also have the best defence in English football having conceded a measly five league goals this season. Sunderland’s defence is not as watertight and it starting leaking goals after just 11 minutes as Morgan Schneiderlin eased past Wes Brown, with the ball falling to the edge of the Sunderland box, where Argentina international Vergini thrashed the ball into the corner of his own goal with deadly accuracy. It did not take the hosts long to double their lead as Steve Davis was released down the left and crossed for Pelle to tap home from close range to continue his impressive form. Shellshocked Sunderland looked like they might peg their hosts back immediately but goalkeeper Fraser Forster was equal to a well-struck Sebastian Larsson free-kick. Poyet was left angered when his side were denied what appeared to be a clear penalty as Forster cleaned out Steven Fletcher after the Scotland forward had latched onto Lee Cattermole’s through ball – but referee Andre Marriner simply signalled for a goal-kick. The Uruguayan’s mood was not helped as Southampton added their third from the very next attack. Tadic crossed from the left and picked out an unmarked Cork, who got enough on his shot to force it past Vito Mannone. Pelle should have done better with a chance on the stroke of half-time but cut his effort well wide of goal as Saints continued to dominate. Southampton came close to extending their lead early in the second half as Shane Long squared to Tadic inside the box, but the Serbia winger saw his shot cleared off the line by Patrick van Aanholt. The fourth goal duly arrived and it once again came courtesy of a Sunderland own goal as Mannone got a strong hand to a low Pelle shot, only for the ball to squirm over the line off half-time substitute Bridcutt. The misery continued for Poyet and his players as Pelle soon made it five, slotting home first time having been played in by Tadic – although he did balloon a hat-trick opportunity high and wide soon after. Tadic was soon on the scoresheet himself as he was gifted possession by a poor Mannone clearance and swept the ball in for his first Premier League goal. Sunderland were in pieces by this stage and Southampton showed no mercy, adding a seventh just seconds later as substitute Wanyama thrashed an effort past the hapless Mannone. Still it continued and Mane was the next to get in on the act as the Senegal man hit his first Saints goal, with Tadic again supplying the ammunition from the left flank. There was to be no record-equalling ninth for the hosts but this was a signal of intent from Koeman’s side as they look to prove their impressive start is no flash in the pan, with the huge victory taking them third in the table and leaving Sunderland in abject misery. Ronald Koeman well and truly disproved the manager of the month hoodoo as his Southampton side decimated a woeful Sunderland outfit 8-0.