O'Shea's place in Wednesday's team to face Hannover 96 in the second match of the Black Cats' tour of Germany is already in doubt.
The 30-year-old, who started at right-back, only lasted 34 minutes of the 1-1 draw with German third division side Arminia Bielefeld yesterday, when he was taken off as a precaution.
O'Shea was making his first outing since moving from Manchester United a fortnight ago, having been given extra time to prepare, rather than face York City last Wednesday.
Bruce is hopeful the Irishman will be available for the rest of the German trip, with the final match scheduled at Borussia Moenchengladbach on Saturday.
It was a decent first work out for five more of Bruce's summer signings. Seb Larsson, David Vaughan and Ji Dong- Won all played significant parts at the Schuco Arena before being replaced.
Then Craig Gardner and Connor Wickham were brought on, with the latter catching the eye with a number of nice touches.
I was happy with how things went it was a good fitness exercise for us, said Bruce.
There were a lot of tired bodies out there, but that obviously happens early in pre-season.
We've been working extremely hard and there were a lot of things which pleased me.
It was a good work out, all in all.
Bruce also expects the man Wickham replaced, Ji, to shine on Wearside given time, knowing just how much upheaval the South Korean has had since his switch from Chunnam Dragons was finalised.
Bruce said: It's difficult for the boy and you have to remember he is only 20-years-old.
What would we be like going to play football in Korea
It's a different culture, a different language.
The one thing is that it has a universal effect. The rules and the game are the same wherever you go.
The culture and learning the language is the most difficult thing for Ji.
He's an outstanding talent and being out here in Germany with the squad will do him the world of good.
It was Ahmed Elmohamady, whose season-long loan was turned into a permanent arrangement this summer, who was left wondering what he had done wrong in the second half.
The Egyptian was penalised for a push by referee Christian Fischer and Bielefeld's Eric Agyemang converted the controversial 63rd-minute spotkick before Sunderland responded and equalised.
Larsson, whose performances on the right will be key in the Premier League, floated over the corner. Michael Turner flicked it on and Stephane Sessegnon levelled 18 minutes before the end.
Sunderland (4-5-1): Mignolet, O'Shea (Ferdinand 34), Bardsley, Turner, Bramble (Elmohamady 56), Cattermole (56), Larsson (Tounkara 88), Vaughan (Gardner 61), Dong-Won (Wickham 46), Malbranque (Sessegnon 61), Richardson (Colback 61).
Subs (not used): Pickford.