Sunderland are gearing up for a very busy summer in the transfer market.

With the club looking to secure promotion it means that there's going to be a number of incomings and outgoings at the Stadium Of Light as Lee Johnson looks to improve his squadd.

Kevin Phillips suggested to Football Insider that Sunderland could consider a move for Jermain Defoe.

The veteran striker is out of contract this summer, and while Rangers are holding talks over a new deal, it remains to be seen where he'll be playing his football next year.

If Sunderland were to make a move there would certainly be a number of knock-on effects.

Here are some of the potential impacts that Defoe's arrival could have at the Stadium Of Light.

No need to find a new striker

The main subplot going into the summer is the future of Charlie Wyke who has been linked with a move away.

If the 30-goal attacker does leave the club then it means that Sunderland will need to splash out on a new striker to lead the line, however if Jermain Defoe is available then it means that they'll have one less signing to make.

Given his history at the club, Defoe could prove to be a risk-free addition.

A change of system

Sunderland's system has been based on playing a fairly direct style and utilising Charlie Wyke's strengths in the box.

While Jermain Defoe is a top-level talent, there's no escaping that he won't offer the same sort of threat in the air.

If Defoe was to sign then Lee Johnson may have to adapt his playing style to suit the player - something that I'm not entirely sure he'd be happy about.

A blow for Ross Stewart

Jermain Defoe's arrival would be a big blow for Ross Stewart.

The 24-year-old is hoping to be Sunderland's main man next term but if the Rangers veteran does arrive them it'll surely push the former Ross County attacker down the pecking order.

Stewart won't be happy about that and that will surely be a consideration.