Former Chelsea captain Ray Wilkins believes the club could struggle following the departure of manager Jose Mourinho.
The Portuguese left Chelsea in the early hours of this morning 'by mutual consent', according to a club statement, and Wilkins fears for their future.
'I'm absolutely astounded at what's happened,' he told Sky Sports News.
'I don't really see the sense in it to be honest, let's hope they've got someone lined up.'
Asked if he agreed Mourinho was the best manager in the game, Wilkins added: 'I would say that would be a fair comment - obviously they will have to look for someone who can hold the reins.
'Winning football matches is what the game's about and he is a winning manager who puts a winning mentality in players' heads and they go and win things.'
Another former Chelsea player, Gavin Peacock, was also worried.
He told BBC Radio Five Live: 'I think that half the team will have been affected badly and it's going to be hard to get that team spirit that Jose managed to manufacture.'
Former England manager Graham Taylor believes the beginning of the end came when Michael Ballack and Andriy Shevchenko were brought in, reportedly against Mourinho's wishes.
Taylor told BBC Radio Five Live: 'Once you take away the authority the manager has in signing players, you're on a slippery slope.
'What I would say about Mourinho is his record is with underachieving players and when Shevchenko and Ballack came in, it disturbed the balance.
'They've never looked as fluid and that's because the manager probably did not himself believe that is the way they should be playing.'
Portsmouth manager Harry Redknapp, who worked with Grant at Fratton Park, backed the former director of football to succeed.
Redknapp admitted Mourinho's exit was a shock.
'It was a complete surprise, amazing to me because he's done such a fantastic job at Chelsea in the last few years,' he told Sky Sports News.
'It was a massive surprise but I knew Avram had gone there and I thought `I can see them pushing him into that position', he was the obvious candidate for me.
'They've got a game on Sunday and I thought someone is going to have to take charge. Avram's there, he's experienced and knows the game, and I felt I could see him stepping in.
'Long term, I'm not sure. I don't know what will happen.'
If Grant takes the job long term he will be expected to produce more entertaining football than Mourinho and Redknapp continued: 'Avram will want to pick a winning team, that will be the main priority.
'Avram likes to play, and there's no shortage at Chelsea of talented players so I'm sure he'll try to get them to play.
'But Manchester United away, it doesn't come any tougher.'
'It's a great chance for him. I'd love to see Avram do well, go in there and be a big success. He's a smashing guy.'