Jonny Evans has told Manchester United that they cannot keep giving opponents a head start and said their defence must become harder to breach.
Evans scored his second goal of the season as United came from 2-0 down to beat Braga in the Champions League at Old Trafford.
But despite his side maintaining their 100% start to their European campaign, manager Sir Alex Ferguson said: "I can't understand our defending."
United have trailed in eight of their 12 matches in all competitions this season, and Northern Ireland international Evans believes they are having to stage too many comebacks.
He said: "We lost the two goals early doors so we were glad to get the result in the end. It's happened quite a lot and is becoming a bit of a habit.
"Hopefully it's something we can eradicate, as we don't want to give ourselves that kind of deficit at the start of games. We need to get a better start in future, especially at Chelsea on Sunday."
Evans was the senior defender in a new-look back four against Braga, partnered by midfielder Michael Carrick and flanked by Rafael da Silva and Alexander Buttner as Ferguson omitted the experienced Rio Ferdinand and Patrice Evra.
Chelsea have a four-point lead at the Premier League summit, but the European champions were beaten 2-1 in Donetsk on Tuesday and Evans noted that Blues boss Roberto di Matteo did not rest any of his regulars.
He said: "Chelsea always seem to play their full-strength team in most games. So maybe it gives us a wee bit of an advantage going into the game, but it's going to be a tough down there - it always is. It's up to us to have a good performance."
Evans has been impressed with the way the new-look Chelsea have proved prolific as they have won seven of their eight league games this season.
He said: "You can see the way they have been scoring their goals this season. They scored four again at the weekend [against Tottenham] so it's going to be a tough game. I don't think our record has been great down there over the last few seasons."