Swindon have rejected a £600,000 bid from Rotherham United for midfielder Massimo Luongo, BBC Wiltshire reports.
He made 53 appearances last season and was part of Australia's squad for the World Cup in Brazil.
Swindon chairman said the Millers' offer for Luongo was a "long way short" of their own valuation.
The Sydney-born midfielder is contracted at the County Ground for another two years.
Rotherham were promoted to the Championship via the play-offs last season and have added 11 new players to their squad over the summer.