Philadelphia registered 19 shots, seven of which were on target, compared to seven shots and one on goal for Sporting, but a strong performance from Sporting goalkeeper Jimmy Nielsen preserved a point for the visitors.
Nielsen came up big in the 27th minute when Philadelphia striker Jack McInerney fired from close-range and again two minutes later when he dove to his right to knock away a well-taken free kick from striker Carlos Ruiz.
The Union kept pressing after the break, nearly breaking the deadlock in the 72nd minute when a cross from Le Toux found Ruiz, who headed it off the crossbar.
Five minutes later, Justin Mapp fired from point-blank range, but once again Nielsen was up to the task.
In the 80th minute, Le Toux dribbled into space blasted a low shot that skidded inches wide of the post.
Sporting's best offensive chance of the night came in the 15th minute when Kei Kamara capitalized on a giveaway in the back, taking two touches before firing just wide of the far post.
The Union return to action Saturday at PPL Park against Chivas USA. The 8:00 p.m. match will air on 6abc.
Sporting KC -- Jimmy Nielsen, Chance Myers, Julio Cesar, Matt Besler, Seth Sinovic, Kei Kamara, Luke Sassano, Davy Arnaud, Birahim Diop (Stephane Auvray 72), Omar Bravo (Michael Harrington 63), Teal Bunbury (C.J. Sapong 46).
Substitutes Not Used: Korede Aiyegbusi, Milos Stojcev, Shavar Thomas, Eric Kronberg.
Philadelphia Union -- Faryd Mondragon, Sheanon Williams, Danny Califf, Carlos Valdes, Jordan Harvey, Justin Mapp (Roger Torres 78), Brian Carroll, Jack McInerney (Keon Daniel 59), Veljiko Paunovic (Amobi Okugo 65), Sebastien Le Toux, Carlos Ruiz.
Substitutes Not Used: Michael Farfan, Juan Diego Gonzalez, Stefani Miglioranzi, Zac MacMath.
KC -- Julio Cesar (caution; Reckless Tackle) 28 PHI -- Veljiko Paunovic (caution; Simulation) 31 KC -- Jimmy Nielsen (caution; Delaying a Restart) 92+
Referee: Terry Vaughn
Referee's Assistants: Greg Barkey; Jason Cullum
4th Official: Jose Carlos Rivero
Time of Game: 1:50
Weather: Partly Cloudy-and-80-degrees
(Copyright 2011 Philadelphia Union. Reprinted by permission)