Slaven Bilic claims having former Southampton captain Jose Fonte in West Ham's ranks proved crucial in masterminding a 3-1 win at St Mary's Stadium.
After Manolo Gabbiadini's debut goal gave hosts Saints an early lead on Saturday, Andy Carroll, Pedro Obiang and Mark Noble netted as West Ham came from behind to claim three important points.
The game saw Fonte, who joined West Ham in the January transfer window, head back to his old club and Bilic picked the brains of the 33-year-old before the Premier League clash to gain an edge.
"It is good to find out some inside things and he helped us with that," Bilic was quoted as saying by BBC Sport.
"It was very special for him and to come here and play so good, it makes it a little bit more special for him than the other guys."
Fonte himself admitted his return was emotional, but the Portuguese was adamant he felt no regret about leaving the south coast club.
"I always gave my best for Southampton, my sweat and blood, so my conscience is clear," he added.
"It was almost eight seasons so it was tough but with the help of my team-mates and [the] West Ham supporters the most important thing was achieving what we got - the three points."
West Ham have endured a turbulent campaign to this point, including the departure of star player Dimitri Payet, but Bilic insisted his side remains united.
"We have a team that is working hard for each other," he said.
"We have a brilliant atmosphere in the dressing room, not because Payet left, but because we have won six of nine. It is a crazy league and there are 42 points to play for.
"There are crazy results and that is why we have to keep playing as we are."
The result condemned Southampton to a sixth loss in seven league games and left boss Claude Puel calling for defensive improvement.
"In the second half we had many chances but without the possibility to come back. We have the quality to play, to score, now we need to keep a clean sheet," he said.
"We have to correct this and find a clean sheet and find confidence about the situation.
"It is important to give confidence to the squad about the defensive chances; we can't replace the best defender in the Premier League," he added, referring to the expected absence of Virgil van Dijk for up to two months with an ankle injury.