Celtic manager Ronny Deila watched Aston Villa striker Libor Kozak score twice in an under-21 match on Monday.
Assistant manager John Collins revealed Deila had travelled to Villa Park to see the Czech Republic international, 26, face Derby's Under-21 team.
"Ronny's gone down to have a look at him and he's scored a couple of goals but there's nothing imminent," said Collins.
"We're looking to strengthen all over, to be honest."
Villa paid Lazio about £7m for Kozak in September 2013, with the 6ft 3in centre forward signing a four-year deal.
He broke his leg during a training session at the beginning of January 2014 and was out for 19 months.
This season, Kozak has featured just once for Villa - coming on as a second-half substitute in a League Cup win over Notts County.