Newcastle are fourth on 19 points after the 25-year-old France midfielder curled home a shot in the 81st minute, his first goal for the club since his move from Lille.
Liverpool's drive for a top-four place stalled when they were held to a 1-1 draw by promoted Norwich City at Anfield, leaving them in fifth place on 15 points.
Newcastle manager Alan Pardew told the BBC: "It was a really good effort by Wigan, they were faster than us at times. It needed a bit of magic and it was a great goal, Yohan's technique was top class."
Liverpool dominated for long periods but, apart from that goal, could find no way past Canaries 'keeper John Ruddy who made a series of brilliant saves, including one in the fifth minute of stoppage-time from Luis Suarez.
Norwich's goal came after an hour when substitute Grant Holt marked his 100th appearance for the club with a thumping header, taking full advantage of poor keeping from Pepe Reina.
Ruddy, who had an oustanding match back on Merseyside where he used to play for Everton, told ESPN: "I'm just delighted with the point. I thought we rode our luck a bit in the first half, but in the second half we were a different animal."
Wolves scored twice in the last five minutes through Kevin Doyle and Jamie O'Hara to end a run of five successive defeats with a 2-2 draw with Swansea.
"We have played better in the last five games and got nothing," McCarthy said. "We needed a break, and hopefully that is it.
"I'm not sure we are jumping around for joy as it has been a difficult day for us, but when you pick the bones out of it, it's a good point."
After Darren Bent gave Villa the lead with a 23rd-minute penalty, the match effectively turned when Villa defender Chris Herd was sent off for what looked like an innocuous tussle with West Brom's Jonas Olsson.
