There were three changes from the Portsmouth defeat.
In came Callum Doyle, Alex Pritchard and Dan Neil, with trio Bailey Wright, Leon Dajaku and Corry Evans missing out.
Neither Dajaku, Evans, Aiden McGeady, Lynden Gooch didn’t make Lee Johnson’s squad due to injury issues.
Gillingham took the lead through a Danny Lloyd penalty but O’Brien equalised in the dying embers of the first half after a poor showing from Sunderland.
Tom Flanagan then put Sunderland ahead in the second half before Elliot Embleton was shown a red card.
But Sunderland were able to hold on despite mammoth late pressure to win the League One game 2-1 at Priestfield.
But how did Sunderland’s players fare against Gillingham? Here, The Echo’s Joe Nicholson delivers his verdict on how Lee Johnson’s men rated at Priestfield.
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1. Ron-Thorben Hoffmann - 8
Was quick off his line on a couple of occasions and made a fine sharp stop to keep out Jack Tucker’s strike. Outstanding late save to deny Robbie McKenzie. 8 Photo: FRANK REID 2021
2. Carl Winchester - 6
A frustrating first half but had more of an influence at the start of the second as Sunderland got on the front foot. 6. Photo: FRANK REID 2019
3. Tom Flanagan - 7
Had a tough battle against Vadaine Oliver. Won some important headers and scored his first goal of the season. 7 Photo: FRANK REID 2020
4. Callum Doyle - 7
Stood up to Gillingham’s late pressure as the hosts brought on extra strikers and went direct. 7 Photo: FRANK REID 2020