Neil Lennon has picked out former Celtic team-mate Craig Beattie as a dangerman for Hearts in Sunday's Scottish Cup semi-final.
The striker, who is an injury doubt ahead of the tie, has scored twice in five games since joining Hearts after being released by Swansea City.
"I think there's been an improvement in his game from what I've seen of him this season," said the Celtic manager.
"He's obviously missed a lot through injury, but he looks very strong."
Beattie began his senior career with Celtic, playing alongside Lennon, before being sold to West Brom for £1.25m in 2007.
He failed to become a first-team regular with the Baggies and had loan spells with Preston North End, Crystal Palace and Sheffield United ahead of a permanent move to Swansea in 2009.
His progress was again hampered by injury and he was loaned out to Watford before being allowed to leave the Barclays Premier League club in January.
But Hearts are unbeaten in five games that have featured the 28-year-old since he signed in February and Lennon was impressed with what he saw of the striker in their quarter-final replay victory in Paisley.
"He played very well at St Mirren and played with great maturity," said the Celtic manager, who also highlighted winger Rudi Skacel as a key man for Hearts.
"He was always a good athlete with good pace, but his technique's improved in terms of his build-up play and he's always got an eye for a goal.
"I'm really pleased for him that he's got some consistent playing time now."
However, Beattie missed Hearts' last outing - a 2-1 win over Dunfermline Athletic in the Scottish Premier League - and faces a late fitness test ahead of the Hampden semi-final against Lennon's Cup holders.