Loftus-Cheek suffered an achilles injury during Chelsea FC’s friendly with New England Revolution in a Holocaust Memorial match in USA last week.
The England midfielder will now face up to 12 months on the sidelines with the injury, ruling him out of the Europa League final later this month.
The 23-year-old has been involved in first-team affairs throughout the season as the England international competed with Ross Barkley and Mateo Kovacic for a starting spot.
Loftus-Cheek has often found his path to the Blues team blocked by more experienced players in the past under Jose Mourinho and Antonio Conte.
However, the Chelsea FC star appeared to have established himself as first-choice under Maurizio Sarri in the final months of the season.
Former Chelsea FC winger Nevin admitted that he was particularly disappointed for the Englishman after his untimely injury setback.
“Everything just seemed to have finally slotted into place for Ruben and his game, and then this happened,” Nevin told Chelsea FC’s website.
“I was already licking my lips at what he was going to do next season with his increasing power, improving game awareness, his burgeoning belief in his own ability, allied to a rest and then an entire pre-season under his belt.
“It looked like being phenomenal from day one. Now, however, there is a long lay-off with a difficult physical and mental slog back to full fitness. He has of course had other injuries before but these long-term ones are not the same, there is a different mind-set needed to get through it.”
Nevin added: “He will certainly be helped by the club, especially with any periods when he gets a bit down and even feels uncertain about the future.
“This is totally natural and understandable for most players in that situation, especially younger ones. In my time it was rather different when I had my first and only long-term injury.”
Loftus-Cheek scored six goals and made two assists in 20 games in the Premier League this season.
Sarri’s side managed to finish in third place in the Premier League table ahead of Tottenham Hotspur, Arsenal and Manchester United.
The Blues can win the Europa League for the second time if they beat Arsenal in the final next Wednesday.
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