Burnley 'offer' £12million for Ben Gibson as Middlesbrough sign ex-Leeds keeper

But Boro face a battle to keep Ben Gibson after claims Premier League Burnley have lodged a £12million bid for the defender.

Gibson has been one of the club's standout players in recent seasons, and Boro are unlikely to sell unless a substantial offer is made.

It comes after Lonergan, 34, became Boro's third signing of the summer, joining on a one-year deal.

Lonergan, who has racked up over 400 career appearances, left Leeds United at the end of last season and is likely to act as backup for first-choice keeper Darren Randolph this campaign.

He follows former Sunderland midfielder Paddy McNair and defender Aden Flint through the door at the Riverside.

Following their abandoned pre-season friendly against Sunderland last week, Boro manager Tony Pulis admitted that the club were still hoping to sign "one or two" more players before the end of the transfer window on August 9.

Since then, Lonergan has been the only arrival, while Patrick Bamford has been sold to Leeds.

Bamford's departure might make way for Ipswich Town striker Martyn Waghorn, however, according to the East Anglian Daily Times, Ipswich "will not sanction Waghorn's sale until they have a replacement in the building".

Boro will also been sweating on the future of Adama Traore in the final week of the window, after Pulis made it clear the highly-rated winger has a buyout clause in his contract.

As it stands, no club has met that valuation, but Premier League side Wolves are monitoring the situation and have already had at least one bid rejected.

It is unclear whether Traore will start against Millwall on Saturday after he sustained a shoulder injury against Sunderland last week.

Towering forward Rudy Gestede is also an injury doubt, meaning record signing Britt Assombalonga is likely to lead the line against Millwall.

If pre-season is anything to go by, Pulis will probably stick with a 4-3-3 system at the Den.

There may be some uncertainty in the wide positions, especially if Traore is unavailable.

Academy graduate Harry Chapman impressed in Boro's final pre-season friendly against Hartlepool last week and could be included.

Forward Martin Braithwaite will also be pushing for a starting place, despite spending the second half of last season on loan at Bordeaux.