SUNDERLAND defensive duo Dennis Cirkin and Callum Doyle are being assessed ahead of tomorrow's League One tie with Cheltenham Town. 

The left-back was substituted in the second half of their 1-0 win over Bolton Wanderers due to a suspected concussion. 

Sunderland boss Lee Johnson made four substitutions during the game meaning Cirkin's will have been replaced because of a suspected head injury as per league protocol. If Cirkin is diagnosed with concussion, he will have to spend at least twelve days on the sideline ruling him out for the following two games. 

Players aged between 17-19 must spend at least 12 days out of action in an enhanced care setting according to the FA. 

Cirkin was enjoying one of his best games in a Sunderland shirt laying on the cross to Carl Winchester for his goal after a bursting run down the left-hand side. 

The former Spurs youngster has impressed with the Black Cats and made the left-back position his own in Johnson's side.

If Cirkin is unavailable for the game at the Stadium of Light, it's likely that Niall Huggins will take his place for tomorrow evening's game against Michael Duff's side. 

Meanwhile, Doyle went off close to stoppage time with a stiff back after putting in a mighty performance to keep Bolton out at the Stadium of Light. 

The 17-year-old has started in every League One game for the Black Cats this season but Johnson has Bailey Wright wiating in the wings if Doyle isn't fit enough to feature against the newly promoted side. 

Speaking after the weekend's result, Johnson said: “Dennis was outstanding and you can see now why we signed him.”

“We're still chasing fitness with a few and you can see that in games. It's a bit frustrating and probably the reason we're not able to quite win games by a higher margin.

“With Callum, he had a bit of a stiff back going into the game yesterday and he just needed a bit of treatment ahead of it.

“It's just seized up on him towards the end there I think and so we had to bring him off.

“Whether he's available for Tuesday, we'll have to see.”