Igor Vetokele underwent surgery on Tuesday evening and will be out for two or three months.
After a blistering start to his career in England, the Angolan international has been plagued by injuries for over a year now.
It now seems unlikely that Vetokele will be back to his best until next season.
Charlton’s Under-21 team reached the last sixteen of the Premier League Cup on Tuesday evening. They beat Watford 2-1 at St Albans in an eventful match.
The visitors included Nick Pope, Zakaraya Bergdich, Franck Moussa and Karlan Ahearne-Grant in a strong looking line-up.
Ademola Lookman gave the Addicks the lead ten minutes after the break. Lookman was brought down by Watford skipper, Charlie Rowan, but picked himself up to convert the ensuing penalty.
Karlan Ahearne-Grant doubled the visitors’ advantage two minutes later, when he prodded home at the far post.
Alex Jakubiak pulled one back for the Hornets seven minutes from time, when he broke clear and slipped the ball past Nick Pope, but Charlton saw the game through.
There was a final twist when Jakubiak and Bernard Mensah were sent off in stoppage time, leaving Watford with just nine men.
Charlton: Pope; Barnes, Staunton, Konsa, Edwards; Moussa, Charles-Cook, Aribo, Bergdich; Ahearne-Grant, Lookman.
Subs: Beeney, Assiana, Kelly, Hanlan, Umerah.
Goals: Lookman 55 (pen),Ahearne-Grant 57.
Watford: Gartside; Sesay (Hall 88), Johnson, Rowan, Mason; Smith, Charles (Stewart 62), Byers, Lewis (Martin 77); Jakubiak, Mensah.
Subs: Trialist, Young.
Goal: Jakubiak 83.
Vetokele’s injury may hasten the arrival of an attack minded player at The Valley.