CHESTER, Pa. – Sebastien Le Toux made US Open Cup history and the Philadelphia Union advanced to the semifinals in the tournament's 101st edition with a 2-0 win over the New England Revolution on Tuesday in a game that was delayed an hour due to a severe thunderstorm.

Le Toux, who has seven goals and three assists in his last seven games in all competitions, scored his 14th career Open Cup goal, setting the record for the modern era of the tournament (1995-present).

Conor Casey scored the opening goal for the Union, who will hit the road to face the winner of Wednesday’s FC Dallas-Carolina Railhawks game in the USOC semifinals on Aug. 12.

Shortly after Le Toux’s seemingly benign free kick from the left side off the field bounced off Revolution goalkeeper Brad Knighton’s hands and gave Philly a 2-0 lead in the 47th minute, a storm rolled through PPL Park with dust flying onto the field and players covering their eyes with their jerseys.

The referee halted the game in the 61st minute due to the crazy winds, rain, thunder and lightning.

The Union continued to control the action after the delay, with Aaron Wheeler, Danny Cruz and Brian Carroll all finding great scoring opportunities while the Revs did little in the offensive third. New England’s A.J. Soares was ejected in stoppage time after picking up his second yellow card.

Before the delay, the Union struck first when Casey ran onto a long free kick from Sheanon Williams in the ninth minute, made a quick move around Knighton – a member of the Union’s 2010 expansion team – and slotted one home.

Casey nearly added a second goal in the 24th minute but could not get a good foot on a cross from Ray Gaddis that left Casey wide open in front of net.

Williams was unlucky not to score one of his own in the first half as a vicious 43rd-minute header from the center back struck the crossbar and dropped straight down. New England’s Saer Sene also hit the crossbar in the 38th minute, 27 minutes after having a shot cleared off the goal line by Maurice Edu.

Zac MacMath, who did not start Philly’s first two Open Cup wins as rookie Andre Blake got the nod in goal, made two saves to earn the shutout.

The Union, who opened the tourney with extra-time victories over the Harrisburg City Islanders and New York Cosmos, are back in the USOC semifinals for the second time in three years as they chase their first trophy in club history.

The Revs, who were vying to win their second Open Cup title and first since 2007, have lost five of their last seven games in all competitions, with their only wins coming against the lower-division Richmond Kickers and Rochester Rhinos in the Open Cup.

Tuesday’s game marked the fourth time the Union faced the Revs this season. Philly has gone 2-1 against New England in league play, including a 3-1 win ten days ago.

The Revs return to Gillette Stadium to host Chicago in league play on Saturday. The Union have two upcoming MLS home games on tap – against Colorado on Saturday and the New York Red Bulls next Wednesday.

Dave Zeitlin covers the Union for MLSsoccer.com. Email him at djzeitlin@gmail.com.