Martin O'Neill's side produced one of the shocks of the season on Sunday when they defeated Barclays Premier League leaders Manchester City 1-0 at the Stadium of Light to climb further away from the relegation zone.
Wigan are still in the bottom three but three points on Tuesday could lift them out of it, and they will go into the match with confidence having beaten Sunderland away little over a month ago.
They also showed good spirit to salvage a point from an entertaining draw with Stoke on New Year's Eve, fighting back from 2-1 down in the final moments despite being a man light following the sending-off of Gary Caldwell.
McCarthy told www.wiganlatics.co.uk: "To come back in the fashion we did against Stoke shows how much we've come along in 2011. There's a real togetherness in the squad with a strong belief and long may that continue.
"Sunderland's going to be another really tough game, they've picked up a lot of points since Martin O'Neill took charge.
"We went up there just a few weeks ago and thankfully came away with the three points. So they'll be coming to our home looking for a bit of revenge and we'll certainly be ready for it hoping to start 2012 in the best possible way."
Wigan's leveller three minutes from time stole the headlines after Ben Watson came off the bench to convert the spot-kick with his first touch.
McCarthy had little doubt his fellow midfielder would get the job done, saying: "Ben practises his penalties near enough every day in training.
"He's a great striker of the ball and to be honest I felt confident when I saw him step up. Thankfully he caught it sweet and it proved to be a great penalty."
Caldwell will miss Tuesday's clash as he serves a one-match ban for his red card, and the captain, who is likely to be replaced by Steve Gohouri, will leave a big hole.
McCarthy felt the Scot was a touch unfortunate to be send off, adding: "Sometimes those decisions go for or against you - unfortunately it went against us.
"He'll be a massive loss for us against Sunderland but, at the same time, it's a massive opportunity for someone else to come in who has been waiting for that chance. Hopefully they'll do a job for us."
The Britannia Stadium was a fitting place to end 2011 for Wigan, who secured their Premier League status on the final day of last season with a 1-0 win at Stoke.
This campaign could well require a similar finish but boss Roberto Martinez believes significant progress has been made and has called for more of the same on Tuesday.
He said: "It's been a marvellous year and now we need to carry on going into 2012 with all the good things we've showed and making sure we push for real steps forward off the field, try to get the training ground all sorted and developed, and on the pitch we'll carry on showing the passion and desire that we had at Stoke."