Chris Rolfe (DCU) Chris Rolfe (DCU)

Chris Rolfe, an instrumental figure in D.C. United’s renaissance this season, fractured his left arm in practice Wednesday and will undergo surgery Thursday, the Insider has learned. He will wear a cast for about four weeks. It was not known right away whether he would be able to play while his arms heals.

Earlier in the day, United officials confirmed a report by Deporte Total USA that Rolfe had suffered an arm injury. The club also said at the time that the medical staff was evaluating his condition.

Acquired from Chicago in April, Rolfe is third on the team in goals with six and second in assists with six. He has started 20 of 26 matches, primarily on the left wing.

United, which has rebounded from last year’s three-win season to lead the Eastern Conference with seven weeks left on the MLS schedule, will visit Vancouver on Saturday night and New York on Wednesday.

Rolfe’s injury coincides with Chris Pontius‘s imminent return from a season-long hamstring injury. Pontius, the senior member of the roster and a regular on the left side until injuries derailed his career, has participated in full training sessions for a few weeks and could return to active duty soon, Coach Ben Olsen said earlier Wednesday. However, Pontius has not played in a real game since last fall and will need time to regain fitness and stamina.

Other options on the left wing include Lewis Neal (seven starts), Alex CaskeyKyle Porter and David Estrada. Olsen could also consider forward Fabian Espindola on the left and pair Luis Silva and Eddie Johnson on the frontline. Johnson has played wide in his career, as well.