The Red Devils decided to part ways with former Chelsea and Real Madrid boss Mourinho earlier in the month following a poor start to the season.
United had slipped to eighth in the Premier League under Mourinho and were knocked out of the EFL Cup by Championship outfit Derby County.
Under interim boss Ole Gunnar Solskjaer, Manchester United have won their last two games, scoring eight goals in the process.
Arsenal legend Merson says this upturn in performance should embarrass the players, telling Sky Sports: It is funny how the players are all starting to run around now.
Solskjaer must be one of the best managers in the world!
The players should be embarrassed. They have been making it look easy of late, and Bournemouth wont be able to stop them at Old Trafford.
It is a great run of fixtures for Solskjaer, and they are on a high at the moment, so will make light work of Bournemouth.
They need the clean sheet, but dont look as solid as they once were.
Solskjaer, meanwhile, has urged his team to maintain their momentum with another victory against Bournemouth on Sunday.
He said: When you win, everyone is happy so lets just keep that run going.
Weve got to focus on our performance against Bournemouth and get three points because the last two games have been fantastic.
Bournemouth have slipped into the bottom half of the table after losing three of their last four games and Eddie Howe expects another tough outing for his team at Old Trafford.
Sunday will be a tough game. Whenever you go to Old Trafford its a tough assignment, the Cherries boss said.
Were looking forward to rising to the challenge, theyve had two good results.
Wed love to elevate our position of course, were still in control of what we do this season. Thats important and were always striving to improve.