Johan Mjallby believes Celtic will need "three or four big characters" in their side next season.
The Hoops' interim assistant manager has helped Neil Lennon salvage some pride in what has been a miserable campaign, which saw the Scottish Premier League title surrendered easily to Old Firm rivals Rangers.
However, following a morale-boosting 2-1 win over Rangers at Parkhead on Tuesday night, the Irishman can make it eight SPL wins in a row when they take on Hearts in their final game of the season at Tynecastle on Sunday.
Mjallby, though, has seen enough to know that regardless of whether or not Lennon is appointed permanent manager, money will have to be spent on bolstering the squad.
"I sincerely hope that Neil gets the job," the Swede said.
"But whoever comes in will try and bring in a couple of new players, there is no hiding from that. You need three or four big characters to strengthen every department of the team.
"That's the way I see it at least and I'm sure whoever comes in will see it that way as well.
Hearts' season is also set to end in disappointment after they missed a golden opportunity on Wednesday to close to within a point of arch-rivals Hibernian.
The Jambos played out a goalless stalemate with Dundee United while Hibs and Motherwell were sharing 12 goals in an incredible match at Fir Park.
That put paid to Hearts' hopes of finishing fourth or fifth and qualifying for the Europa League barring a massive goal swing.
Midfielder Ruben Palazuelos said: "You see Motherwell and Hibs draw. If you win, you probably stay there for Europe. These things happen in football."
Palazuelos believes a less eventful season next time round will see Hearts achieve their aims.
"This season has been very, very strange," he said. "Lots of things have happened. Too many injuries, a change of manager."