McClain was seen sitting on the bench talking to a trainer and doctor in the second quarter. The Cowboys said after halftime that the linebacker wouldn't return because of illness and dehydration.
Swanson left before halftime with a knee injury. After his return was initially announced as questionable, an update after halftime said he was done for the game.
Swanson, a rookie who has started at guard, center and tackle for the Lions, had started in place of Larry Warford at right guard. Warford was out with a knee injury.
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