Przemyslaw Frankowski scored for visiting Chicago in the fourth minute of second-half stoppage time for a 1-1 tie with the host Columbus Crew on Saturday.
The Crew (8-15-7, 31 points) is 3-1-5 in the past nine games.
Chicago (8-12-10, 34 points) has lost once in three games.
"We had a chance to kill the game and we didn't," Santos said.
A point-blank save by Room on Micheal Azira in the 82nd minute preserved the lead until the closing minutes. Room had four saves.
Room, a veteran of 12 seasons in the Dutch Eredivisie and the current Curacao national team keeper, was signed by the Crew on July 5 to replace Zack Steffen, who transferred to Manchester City in England's Premier League and is on loan to German club Fortuna Dusseldorf.
Santos continued his scoring splurge with the go-ahead goal in the 27th minute. He dribbled through traffic and unleashed a strike from the top of the box for his 10th goal.
He has five goals and three assists in his past eight games.
The Fire were looking for fourth win in six games, but their woes continued on the road where they are 1-10-4 with a league-low 13 goals scored.
Chicago did pick up its second point of the season (0-9-2) when trailing at the half.
Each team doesn't play until Sept. 14 when the Crew is at Atlanta United and Chicago hosts FC Dallas.