The Revolution were protecting a 1-0 lead - Rajko Lekic scoring his fourth goal of the season in the 38th minute - when the game started changing in the final minutes. Guy replaced right back Kevin Alston (turf toe, cramps) in the 78th minute. Four minutes later, A.J. Soares appeared to have made a clean tackle, but was red-carded by referee Terry Vaughn. Darrius Barnes moved to central defense and Mansally, who entered the match as a 34th-minute replacement for Stephen McCarthy (shoulder), took over at left back.

Meanwhile, Sporting was adding strikers Omar Bravo, Teal Bunbury, and Birahim Diop. Guy held his own against Bravo, and Mansally stayed with Kei Kamara, but Bunbury converted the tying goal in the 89th minute.

“All kinds of changes were forced upon us, but we defended well,’’ Revolution coach Steve Nicol said yesterday. “They [Guy and Mansally] both showed good professionalism. Bravo is a great player, but Ryan did a decent job against him, he showed grit and determination.

“In the first half we did great, we never gave them any chances, got ahead, the whole shebang. They’re the home team so you know they are going to come at you and they came forward in the second half. They probably deserved a draw but the way it came about kind of sticks in your throat. A.J. has got the ball, and the [red card] is just a bad decision, absolutely the wrong decision. It’s bad enough we have to play the last [12] minutes without him, but we lose him for next week, as well.’’

The Revolution (4-9-9, 21 points), who earned 5 points in three away games beginning July 20, host Chivas USA Saturday.

“It always makes it harder playing with 10, then to lose a goal like that,’’ Nicol said. “The ball’s bouncing all over the place and there is a suspicion of hand ball, and we end up with a point. They had a lot of pressure and sent a lot of guys forward, but I thought we defended well. In the second half, they got behind us maybe twice, and that was it.’’

Lekic finished off a Matt Reis clearance, running ahead of the defenders and lashing a side-foot shot past Jimmy Nielsen.

“That was a striker’s goal, taken perfectly, good timing and all that, as the goalie’s coming forward,’’ Nicol said. “A proper striker’s goal. To be fair [to Lekic], we haven’t given him opportunities to show what he’s capable of. He’s playing up there alone. Initially we got him as a guy we would make chances for and he would score.’’

The Revolution could go to a two-striker attack soon, though.

“Hopefully, we’ll have something to tell everybody this week,’’ Nicol said of a possible signing. “I’m optimistic, we think it’s done but too many times before, at the final hour, everything’s gone pear-shaped. Until he’s signed, sealed, and delivered, we’re keeping our mouths closed.’’

Frank Dell’Apa can be reached at f_dellapa@globe.com.