Everton boss Sam Allardyce warned his players they must improve on their display against Bournemouth if they are to get a result against Manchester United.
The result brought an end to eight games without defeat for Everton under Allardyce.
Next up are United, who travel to Goodison Park on the back of three straight draws to Southampton, Burnley and Leicester, but Allardyce remains wary of Jose Mourinho's side.
When asked if he feels United are vulnerable, Allardyce replied: "Only if we play our best. If we play our best then we will have a chance.
"This is why losing this game [against Bournemouth] is so disappointing.
"If you are going to be successful in the Premier League you have got to beat the teams below you and you certainly don't lose against them.
"We have gone and lost against Bournemouth and it puts more pressure on you to make it up somewhere and that would always have to be against a bigger club.
"We have got to pick ourselves up and then look forward to Man United and then Liverpool."
Wayne Rooney was introduced at half-time against Bournemouth after missing two games with the flu and Allardyce expects the 32-year-old to be fit to face his former side.
When asked about if he expects him to be available, Allardyce said: "Yes, it is only a virus, not an injury so getting 45 minutes in will be good for him.
"I'm juggling things. James McCarthy is not match fit. Yannick (Bolasie) is not match fit. I would love all these players to be super match fit at the moment and contributing more.
"The injured players that are still not fit yet will hopefully be back sooner rather than later and the players we have at the moment will certainly have to play better on Monday than they did today."
Senegal international Gueye returned to the starting line-up against Bournemouth after sitting out the goalless draw against West Brom on Boxing Day with a hamstring injury.
The midfielder got on the scoresheet just before the hour mark before being withdrawn in the 71st minute with the hope of preserving him for Monday's game against United.
Allardyce said: "He said he was okay. We had to believe what he said. We were going to bring off a bit sooner then he said he was okay again.
"Then he felt a bit tight so we brought him off in the hope he will not be injured for Monday because I think he is a big player that we miss when we have not got him."
Allardyce also confirmed negotiations are ongoing for Besiktas striker Cenk Tosun.
Earlier this week, Sky Sports News reported Everton officials flew to Turkey on Friday night in an attempt to finalise a deal.
"I know there is some negotiation going on," Allardyce said, when asked for an update. "I don't know where it is and where it has got to at the moment."