The games will be part of the Albufeira Cup, with Roy Keane's men playing Sporting and Vitoria de Setubal, at the Albufeira Municipal Stadium in July.

The Black Cats will kick-off their tournament against Sporting Lisbon on Sunday, July 20 (9pm local time).

And they'll follow that up with a game against Vitoria de Setubal on Wednesday, July 23 (kick-off to be confirmed).

Sporting – who, along with FC Porto and Benfica, are one of Portuguese football's "big three" – finished Super Liga runners-up this season, 20 points behind winners Porto.

Vitoria de Setubal, a smaller club who are yet to win the domestic league title, finished sixth this season.

The tour will allow Roy Keane to get his squad the 'warm weather training' which he regards as vitally important, and the trip also has the benefit of having no long-haul flights to contend with.

Keane has taken his players away to train on the Iberian peninsula several times since taking over the reins as Sunderland boss, and his players can expect the planning to have been meticulous.

It means the pre-season programme is taking shape much earlier than is normally the case with four games already named.

The confirmed games for pre-season so far are:
Sporting Lisbon (Portugal) Saturday, July 20; Vitoria de Setubal (Portugal) Wednesday, July 23; Nottingham Forest, Wednesday, July 30, and Ajax, Sunday, August 3.

Further games are due to be announced in due course.