Ibrox club Glasgow Rangers have signed Allan McGregor and Scott Arfield, and former Gers midfielder Barry Ferguson is impressed.
Rangers are reportedly in talks to sign Bournemouth striker Jermain Defoe.
Rangers suffered a huge 5-0 loss to Celtic on Sunday.
Ex-Rangers star Ferguson played with West Ham goalkeeper Hart at Birmingham City.
Glasgow Rangers are reportedly interested in bringing Allan McGregor back to Ibrox this summer.
Rangers are likely to be busy this summer and Scott Arfield is reportedly close to signing at Ibrox.
Brendan Rodgers' Celtic side play host to Graeme Murty's Rangers in the Old Firm clash on Sunday.
Following Rangers' defeat to Celtic in the Scottish Cup, Barry Ferguson has suggested that the weight of expectation is too much for the Gers players.
Rangers legend Barry Ferguson is not pleased with Ibrox club chairman Dave King’s recent statement.
Graeme Murty's Rangers side will be looking to end Brendan Rodgers' Celtic's hopes of back-to-back trebles on Sunday.
Vellios is out of favour at Nottingham Forest, but might he have better luck at Ibrox, where Rangers legend Ferguson is being tipped to return as Caixinha's assistant?
Ferguson may not have won a game in charge of League Two Clyde since November but that has not stopped speculation linking him to Rangers.
The former Rangers captain would certainly be an interesting appointment.