As it stands, United has 24 players under contract. The roster maximum is 28. Not all current players are assured of sticking with the club; a trialist could beat out a holdover. And if, as promised, United signs one or two potential impact players from Latin America or Europe, they would automatically fill roster slots.
Additional trialists are expected for the second stage of camp, beginning Feb. 11 in Clearwater, Fla.
The club will begin a set of preseason friendlies Friday night in Bradenton against Elfsborg, a Swedish club conducting training camp in warm environs.
Bill Hamid: incumbent starter sidelined four to six months with knee injury.
Andrew Dykstra: second-choice keeper who started 13 league matches plus numerous U.S. Open Cup and CONCACAF Champions League games in 2014-15.
Travis Worra: almost all playing time in 2015 rookie season came with third-tier Richmond Kickers.
Chris Konopka: MLS back-up for several years before logging 21 league starts for Toronto FC last season.
Paolo Tornaghi: Nine starts for Chicago Fire in 2012-13 but no first-team appearances with Vancouver in 2014-15.
Bobby Boswell: captain and most experienced center back.
Steve Birnbaum: currently with U.S. national team, expected to report to United on Feb. 7.
Kofi Opare: center back who started 17 league matches last season.
Sean Franklin: first-choice right back.
Taylor Kemp: first-choice left back.
Chris Korb: outside back in late stages of ACL rehab.
Luke Mishu: second-year outside back.
Jalen Robinson: second-year homegrown who plays central and right.
Liam Doyle: Fourth-round draft pick, 6-foot-4 center back from Isle of Man and Ohio State, seeking to earn contract.
Nick DeLeon: veteran wing might end up playing centrally this season.
Lamar Neagle: acquired from Seattle, likely to start on left flank.
Patrick Nyarko: acquired from Chicago, strong option to start on right flank.
Markus Halsti: Finnish national team veteran will fill a central role.
Davy Arnaud: Gritty central player who missed last two months of 2015 season with concussion. “We’ll go day to day,” Olsen said. “The number one priority is his health for the long term.”
Miguel Aguilar: promising right wing enters his second season.
Jared Jeffrey: defensive midfielder made just two league appearances last year.
Collin Martin: homegrown attacking player vying for playing time.
Julian Buescher: German native, first-round draft pick from Syracuse, two-way player, under contract via Generation Adidas deal.
Ariel Rodriguez: 29-year-old defensive midfielder from Alajuelense was alternate on 2014 Costa Rican World Cup roster.
Kevan George: Four seasons, 28 league matches with Columbus Crew, defensive midfielder, Trinidad and Tobago national team.
Paul Clowes: Manchester City youth system, second-round draft pick from Clemson, defensive midfielder, seeking to earn contract.
Rob Vincent: 25-year-old Englishman scored 21 goals in 30 matches across all competitions for third-division Pittsburgh Riverhounds last season.
Paul Torres: 24-year-old Bethesda native with DCU academy ties played at University of Maryland, then Sweden and Norway.
Santiago Dittborn: 23-year-old Chilean who plays centrally, Universidad Catolica youth system, most recently with San Marcos.
Konstantine Kolokotronis: 23-year-old attacker from Sacramento, attended UC Davis, signed in Greece in August 2013, played second division.
Chris Rolfe: Club MVP in 2015, inventive and technical player likely to play higher in formation. Age: 33.
Fabian Espindola: Creative, dynamic floating attacker looks to rebound from 2015 suspension, injuries. Age: 31 in May.
Alvaro Saborio: Target striker scored four goals in 12 league matches after RSL trade. Age: 34 in March.
Conor Doyle: Appeared in 25 league matches (10 starts) last year, two goals.
Andrea Mancini: 23-year-old son of Roberto Mancini, Inter Milan’s manager. United’s primary investor, Erick Thohir, is Inter’s majority shareholder. Andrea was in Inter, Bologna and Manchester City youth set-ups. In past four years, he’s played for Oldham, Fano (Italy), Vallodolid B (Spain), Budapest Honvid, Szombathelyi Haladas (Hungary).
Behind the scenes, United announced the hiring of Stewart Mairs as director of soccer strategy and analysis — a position created this winter to complement the technical staff. The British-born Mairs will focus on recruitment, oversee advanced scouting and match preparation. He will report to General Manager Dave Kasper.
“I have consulted with him on various analytics projects during the past several years,” Kasper said, “and his work has been outstanding.”
In addition to working for Prozone, a performance analysis and statistics company based in Britain, Mairs worked as a consultant and as head of performance analysis for the U.S. women’s national team during the 2012 Olympics and 2015 World Cup.