Everton boss David Moyes has praised the impact Nikica Jelavic has made in his short time at Goodison Park, labelling the striker a 'silent assassin'.
The Croatia international moved to Merseyside on transfer deadline day in January in a £5million deal from Rangers.
A groin injury hampered his first few weeks at the club but since returning to full fitness he has been in fine form, grabbing three goals in six starts.
That has helped the Toffees maintain a run of form that has seen them lose just twice in 15 matches to rise up to seventh in the table - above neighbours Liverpool - as well as setting up an all-Merseyside FA Cup semi-final at Wembley next week.
Moyes believes the goal threat created by Jelavic has been the catalyst for yet another post-Christmas revival but admits even he is surprised at how quickly the 26-year-old has taken to life in the Premier League.
"Nikica has given all the players a lift because we have badly needed a different kind of forward here for a couple of seasons," said the Scot.
"I think that he feels he has something to prove. He's scored goals in Austria and Scotland, but this is a step up for him.
"I knew we were getting a Croatian international, who will be going to the Euros, and he's settled in really quickly.
"To be honest, he's a bit of a silent assassin. He's pretty quiet, walks round with a smile on his face, and it's surprised me how quickly he has taken to it.
"He's been getting his one or two chances a game and there's a bit of 'ticking over' with him at the moment. I just hope that keeps going."
Jelavic's arrival capped a busy and successful January transfer window for Moyes and Everton.
For many the winter window is not seen as the ideal time to buy players but after selling Diniyar Bilyaletdinov to Spartak Moscow the Toffees were able to bring in Landon Donovan and Steven Pienaar on loan as well as Darron Gibson and Jelavic on permanent deals.
Moyes is keen to praise the new recruits for lifting the players' spirits after a difficult first-half to the season.
He also admits he had already eyed Jelavic prior to his big-money move to Ibrox two years ago.
"I went to see Nikica when he was at Vienna, but chose not to take him then," added Moyes.
"Up to January 28 this year, I didn't think we'd be buying anyone. We had £5m to spend and had to do so very wisely.
"But all the players who came in January - Darron Gibson, Steven Pienaar and Landon Donovan, when he was here - have made a big difference."