Benfica have made an offer for Celtic goalkeeper Fraser Forster, according to Sky sources.
Benfica boss Jorge Jesus has made an undisclosed bid for Forster but Celtic manager Neil Lennon is determined to keep him at Parkhead.
Forster impressed when the two clubs met during last season's Champions League and the Portuguese club have moved to try and secure the 25-year-old before the transfer window closes.
Lennon, who has lost Gary Hooper, Victor Wanyama and Kelvin Wilson during the summer, has been quoted as saying his first-choice keeper is not for sale.
The giant keeper, who signed a four-year-deal with the Hoops in June 2012 after two years on loan from Newcastle United, has also been linked with a move back to the Premier League.