Ange Postecoglou has cooled the hype over the signing of Aaron Ramsey – until he makes his mark on the pitch.
The Scottish Premiership leaders sealed a sensational deadline day swoop for the former Arsenal midfielder as he arrived from Juventus on loan.
But Postecoglou, whose Celtic side take on Rangers on Wednesday night in a huge title clash, says his big reputation has no guarantee of success.
He insists signing players isn't an "exact science" and that the Ibrox side should wait until he delivers on the park before getting excited.
The boss also insisted unknown players can often be as impactful as big names – such as Kyogo Furuhashi who has been a smash-hit at Celtic Park.
When asked by Sky Sports about Ramsey, Postecoglou said: "I don't spend a lot of time focusing on what other clubs are doing.
"For us, it's about how we build our squad, and if we're building a squad that can be successful then that's the most important thing.
"Any time opposition sides bring in players and strengthen, it makes the competition better.
"But with all these things, no-one had heard of Kyogo Furuhashi before I brought him in. It's all about the impact you make when you play.
"Signing players is not an exact science as we've found out.
"It's more about performances. That's when I take notice, when new signings make an impact on the field rather than when they sign."
