Ben Olsen checking his options at RFK Stadium last month. (Thomas Simonetti/The Washington Post)

Upon agreeing to a contract with D.C. United last week, MLS veteran goalkeeper Tally Hall joked with Coach Ben Olsen.

“I bet you never thought you’d have to sign five goalkeepers.”

Olsen shook his head.

It’s standard practice for a team to have two keepers game-ready and a third in development. Five over the course of a full season is unusual. Five after one month of the regular season is unfathomable.

But that is where United stands after starter Bill Hamid underwent knee surgery in January and back-up Andrew Dykstra injured his back following the opener. Travis Worra, a second-year pro, and Charlie Horton, who was acquired late in preseason, climbed the depth chart.

While Worra was fine as the new starter, United recognized the need for an experienced option. So the club turned to Hall, 30, who played in two MLS Cups for the Houston Dynamo and started most of the 2015 campaign for Orlando City before the expansion outfit dumped him last fall.

With Horton (concussion) joining Hamid and Dykstra on the injury list, Hall accompanied the team to San Jose last weekend and watched Worra make a sterling last-minute save on Chris Wondolowski, MLS’s career scoring leader among active players, to preserve a 1-1 draw. With Worra in rhythm, Olsen said Friday that the former New Hampshire Wildcat will make his fifth consecutive start Saturday when United (0-2-3) faces the Vancouver Whitecaps (2-2-1) at RFK Stadium.

“When you do well, I try to reward you,” Olsen said of the goalkeeping competition. “Sometimes it’s as simple as that.”

If Worra falters at some point, Olsen will call on Hall, who is seeking to regain form after almost six months without playing in a competitive match.

“I’m confident in what I am capable of,” he said, “so now it’s just a matter of working hard and waiting for an opportunity.”

Hall was among MLS’s best during a four-year tenure as Houston’s first-choice keeper, earning all-star accolades and U.S. national team call-ups. He tore the ACL in his right knee late in the summer of 2014 and, during the recovery process, was traded to Orlando. He debuted with the first-year club last May and started 23 matches before tearing meniscus in the same knee in the penultimate match of the regular season.

Before the injury, Hall said Orlando had planned to rework his contract, which was set to expire after the 2016 campaign. In the offseason, however, the club decided to go in a different direction.

“A lot of people put it on my injury, but it’s my meniscus, so if you don’t offer contracts to people with meniscus injuries, you are going to cut down on a lot of guys under contract,” he said. In the big picture, “if you want stability in your life, this isn’t the profession for you. It’s what I signed up for. As frustrating and surprising as it was, you move on and find something else.”

It took a while. He trained informally with his hometown club, the Seattle Sounders. United’s predicament led to formal workouts in Washington and, ultimately, one-year contract at a much-lower rate than his $215,000 base salary in 2015. Terms were not disclosed.

“Every day,” Olsen said, “he gets closer and closer to the Tally Hall we all know.”

Hall said the injuries were only temporary setbacks.

“I tell people – and I don’t think they believe me, and sometimes I don’t believe it myself – but my knee feels better than it did last year, and last year I was making some of the most athletic saves of my professional career,” he said. “I feel I can get back to being more athletic and dialed in. I don’t see a reason that will change; I think I will continue to improve.”

Meantime, Hamid is on pace to rejoin full workouts sometime next month. (Dykstra is out until June.)

“There’s a group of goalkeepers, and I think they all understand that when Bill gets back to his form, he is our number one goalie,” Olsen said.

United notes: The Whitecaps are missing central midfielders Pedro Morales (groin injury) and Matias Laba (red card suspension). Morales’s four goals lead the league and Laba started the previous five matches. … After conceding five goals in their first two matches, the Whitecaps have allowed one in the past three games and posted consecutive shutouts against Houston and Los Angeles. …

United midfielder Patrick Nyarko, who left the San Jose game after falling hard on his lower back and hip last week, trained most of the week. … Midfielder Markus Halsti (knee) completed his first full week of regular season training and is a few weeks from match consideration. … Midfielders Paul Clowes and Miguel Aguilar are the most likely candidates to join the third-division Richmond Kickers for Saturday’s USL home match against the Rochester Rhinos. … Rookie midfielder Julian Buescher is recovering from a calf injury. …

Italian forward Andrea Mancini, who signed last week, is not expected to make the game-day roster anytime soon.

“He tactically understands the game and technically is very good,” Olsen said. “Athletically it’s going to take a little time to catch up to the speed of our trainings and the league.”

Mancini, 23, is the son of Inter Milan Coach Roberto Mancini. Inter Milan is owned by Erick Thohir, United’s primary investor. …

Richie Burke will coach D.C.’s under-23 team again this summer, the club announced, but instead of competing in the fourth-tier Premier Development League, United will play an independent schedule of about a dozen matches. One proposed game is against a Southampton squad in mid-July at the University of Maryland. United was 8-2-4 last year but decided to drop from the PDL because of late-season scheduling conflicts with players returning to college. …

The game-time weather forecast Saturday calls for 41 degrees, a 37 percent chance of rain and 30-mph wind. … Jorge Gonzalez is the referee.

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D.C. United vs. Vancouver Whitecaps

Where: RFK Stadium.

When: Saturday at 5:30 p.m.

TV: ABC7.

Records: United 0-2-3, 3 points; Whitecaps 2-2-1, 7 points.

D.C. probable starters: GK Travis Worra; Ds Sean Franklin, Bobby Boswell, Steve Birnbaum, Taylor Kemp; MFs Patrick Nyarko, Marcelo Sarvas, Nick DeLeon, Lamar Neagle; F Chris Rolfe, Fabian Espindola.

Vancouver probable starters: GK David Ousted; Ds Fraser Aird, Kendall Waston, Tim Parker, Jordan Harvey; MFs Cristian Techera, Andrew Jacobson, Christian Bolaños, Kekuta Manneh; Fs Nicolas Mezquida, Octavio Rivero.