Andrew Nelson, currently on loan at Harrogate Town, came off the bench to rescue a point for Sunderland U23's in their second Premier League International Cup group game.
Bouyed by scoring his first goal for Harrogate at the weekend, Nelson impressed in his late cameo after Sunderland's other attackers failed to make much headway.
Caretaker boss Robbie Stockdale watched the first half ahead of Saturday's Championship clash with Millwall.
The visitors dominated possession in the opening stages, with Sunderland content to sit off and watch their opponents move the ball across their backline.
They were served early notice of the Legia Warsaw threat when attacking midfielder Grzegorz Aftyka flashed an effort just wide of James Talbot's right-hand post.
Though the Polish side continued to see most of the ball, it was Sunderland who created the best chances, with Joel Asoro an inconsistent threat as he broke in behind the defence.
Right-back Owen Gamble came close with a long-range effort, swerving and bouncing just in front of Szumski in the Legia Warsaw goal. He was able to get behind the effort but was lucky to see it roll just wide of his goal.
His second save just minutes later was far more emphatic, racing off his line to deny Asoro with his feet on the hour half mark.
Two minutes later, his side were ahead, the ball breaking to Robert Bartczak, the left-back who was a menace throughout with his overlapping runs. His side-footed effort comfortably beat Talbot and from there the Black Cats were lucky to reach the break one down as Legia turned the screw.
The second half began at a sedate pace, with winger Luke Molyneux coming closest as his effort from close range was deflected over the bar.
Sunderland were struggling to make much of an impact in the final third and Elliott Dickman acted quickly by removing the disappointing Asoro on the hour mark, with Harrogate Town loanee Andrew Nelson taking his place.
The hosts were able to apply some pressure without creating a clear opening, Nelson shooting tamely wide from range as the game entered the final 15 minutes.
Jack Diamond, whose individual skill on the ball was a bright spot for Sunderland throughout, went close, picking up a Talbot throw on the half way line and breaking towards the box. His left foot effort was weak, however, drifting wide.
They were able to force an equaliser five minutes from time, substitute Nelso scoring with an emphatic finish on his left foot at the back post.
SUNDERLAND XI: Talbot; Gamble, Hume, Beadling, Taylor; Molyneux, Robson, Bale, Diamond (Kimpioka, 80), Greenwood (Connelly, 80); Asoro (Nelson, 60)
Unused subs: Storey, Woud, Hackett, Allan
LEGIA WARSAW XI: Szumski, Turzyniecki, Byra, Welnicki, Bartczak, Cichocki (Wiedlocha, 66), Moneta, Nishi, Praszelik (Bondarenko, 85), Aftyka (Szczepanski,57) Goral
Unusd subs: Kochalski, Bondarenko