The former Hull City and Strasbourg boss was not in charge for the disappointing 2-1 loss against Fulham on Wednesday evening, with Under-21s boss Calum McFarlane once again leading the team.
But Rosenior has had a few days to get to grips with his squad and the task ahead, with Chelsea down in eighth in the table.
A new manager often means new opportunities for players who were perhaps not in favour under the previous regime.
So, here is a look at some of the players who may see their playing time increased under the new boss in the second half of the season.
Andrey Santos
Santos was a revelation last season in France under Rosenior, scoring 10 goals and registering four assists in the league as he helped the club to qualify for the UEFA Conference League. Santos narrowly missed out on the Ligue 1 Young Player of the Year award and sometimes captained the side – a rare honour for a loanee.
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Video credit: TNT Sports
Under Maresca, he found game time difficult to come by, often due to the presence of Enzo Fernandez and Moises Caicedo. However, he did have some standout performances, notably away at Burnley and last weekend when he came off the bench in the 1-1 draw against Manchester City.
Former Chelsea midfielder Joe Cole said on TNT Sports after that win over Burnley: “I thought Andrey Santos was outstanding. It wasn’t so much what he did on the ball. He was very tidy, very efficient.
“But off the ball, we questioned it, didn’t we? We said, ‘How would Chelsea react without (Moises) Caicedo today because of the things that he can do, blocking runs and breaking down play’.
“But he (Santos) was absolutely outstanding. Every time there was a bit of danger, he sniffed it out. Sometimes, I think players have a natural ability in this area, and he seems to be one of those types of players. Chelsea have got Enzo, (Romeo) Lavia, Caicedo, and Andrey Santos as well.”
Rosenior’s formation is, as yet, a mystery, with the Englishman having utilised multiple systems during his managerial career, but whether he uses a midfield two or a three, expect Santos to play far more often moving forward.
Liam Delap
If Rosenior and his staff can work with the existing medical team to ensure Delap stays fit, the next issue is confidence. Something appears to have turned with the striker though. After a solid (if a bit chaotic) cameo off the bench against City, Delap finally opened his Premier League account for the Blues against Fulham. Delap’s form will be key to Chelsea’s second-half of the season and Rosenior’s arrival may be just what he needs.
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‘It is mightily tight!’ – Delap goal wraps up Chelsea victory despite delay
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Malo want
However, because of the return to fitness of club captain Reece James, in combination with Maresca’s preference for inverted full-backs, Gusto has stagnated. But, as demonstrated by his performance against City, when he is played in a more traditional role, he can still be extremely effective.
As previously mentioned, Rosenior has shown himself to be a flexible manager and Gusto is someone who should benefit from that approach, as he should be allowed to play in a far more natural manner.
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‘Chelsea don’t quite know what’s right for Chelsea’ – Hart and Ward on Maresca sacking
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Josh Acheampong
Acheampong has been far from perfect when playing for the first team, but more often than not, he has shown that he belongs, and he has a future at this level. Acheampong is calm, a good reader of the game and tremendous on the ball (both passing and carrying), a true modern-day defender.
With some struggles in the middle of defence this season, could Acheampong be Rosenior’s long-term answer?
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Teenager Acheampong bullets Chelsea in front at Forest
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Shim Mheuka
We end with two academy players who have been standouts this season and might warrant a look from Rosenior, particularly with so many games to be played over the next couple of months.
Shim Mheuka is the leader of the Chelsea academy, regularly captaining the sides he plays in despite only recently turning 18. He has seven goals in seven PL2 games this season and has notched five times in as many UEFA Youth League appearances.
Jesse Derry
Since joining Chelsea in the summer of 2025, Jesse Derry, son of former Crystal Palace and QPR midfielder Shaun, has hit the ground running, instantly becoming a key cog in the youth teams.
Primarily a No. 10, Derry can also play out wide and has 10 goals across the PL2 and UEFA Youth League this season.
Unlike Mheuka, who seems to have a clearer path to first-team minutes, or even centre-back Harrison Murray-Campbell, Derry would have a tough time getting into the first team given the glut of options in those positions for Chelsea, but he is doing everything he possibly can to make Rosenior take a look at him.
