Celtic boss Neil Lennon admits he may have to buy a new left-back after witnessing Emilio Izaguirre suffer a broken fibula.
The club's player of the season last term went down in a heap after a legitimate tackle from Aberdeen's Peter Pawlett during Celtic's 1-0 win on Sunday.
Lennon was visibly disturbed by the injury and, although replacement Charlie Mulgrew impressed in the position, the Northern Irishman admits he now needs cover.
"It's a huge blow for us, you know a player knows straight away and you could see," Lennon told Sky Sports News. "He's not the type of player to stay down.
"It's a fibula fracture and he's being assessed at the minute to see if he needs surgery or not. If he requires surgery it could be three to four months out.
"He was one of our best players last season and we were hoping for more of the same this year.
"Mulgrew came in today and was excellent in his place, but we may have to go and get another one (left-back) now just to add cover there."
Lennon admits he was not yet finished in the transfer market, but will have his work cut out now and plans talks with the club's chief executive, Peter Lawwell, over targets.
He added: "We had one or two in mind - that might now be three - I'll have to speak to Peter and see where we can go with that."
Izaguirre's team-mate, Adam Matthews, spoke on the squad's behalf in wishing the 25-year-old a speedy recover.
He said: "It's obviously a massive blow, he's been a great player for us and he'll be a great miss if he's out for that length of time.
"All the boys wish him a quick recovery and I'm sure he'll come back even stronger."
Aberdeen boss Craig Brown also offered sympathy, as he added: "He gives Celtic a very good dimension down that left-hand side and I was very sorry for him. He lit up the Scottish game last season."
On a positive note, Lennon guided his side to the top of the Scottish Premier League table with the win at Pittodrie, which came via an Anthony Stokes strike on 74 minutes.
Lennon would have liked his strikers to be more clinical in front of goal, but declared himself satisfied with their overall performance.
"It was a great goal, a well worked goal, and I felt on the balance of play we deserved it," said Lennon.
"I would have liked to have been in a more comfortable position because we kept creating really good chances, but decision making was a little bit off today.
"Our possession and passing and the way we worked the ball was very good today so I'm pleased with that and I thought the back four gave us a good platform to work from."