The LA Galaxy pair are two of four players who have had to withdraw from the squad for Wednesday night's match at the last minute due to injury.
On Tuesday, MLS confirmed that LA Galaxy duo Steven Gerrard and Robbie Keane, Toronto FC midfielder Michael Bradley and New England Revolution left-back Chris Tierney had all been forced to withdraw from the league’s annual showpiece due to various injuries.
In their place, Mastroeni, who as the manager of the hosting Colorado Rapids will also coach the All-Star team, has named five alternates, selecting Columbus Crew SC teammates Ethan Finlay and Waylon Francis, Galaxy pair Juninho and Gyasi Zardes and Rapids midfielder Sam Cronin for the new 23-man squad.
Finlay’s absence from the initial squad was a surprise in itself given his stellar displays so far this season, having racked up seven goals and a league-leading 12 assists in 22 games to put himself into the MVP conversation.
On the other side, Gerrard’s inclusion generated a fair amount of criticism when he was selected as one of commissioner Don Garber’s two selections for the game along with Frank Lampard earlier this month, having not seen a single minute of MLS action at the time.
While the 35-year-old midfielder has since made two appearances for LA, New York City FC new boy Frank Lampard is still to make his league debut due to a nagging calf strain which saw him replaced by New York Red Bulls skipper Dax McCarty at the weekend.
Reigning league MVP Keane misses out on the chance to face his former club as well, while Toronto FC star Sebastian Giovinco is also believed to be a doubt for the clash at Dick’s Sporting Goods Park.
Here is the updated roster and predicted starting XI which will be captained by Orlando City SC’s Kaka:
GOALKEEPER: Nick Rimando (Real Salt Lake), David Ousted (Vancouver Whitecaps).
DEFENDERS: Matt Besler (Sporting KC), Omar Gonzalez (LA Galaxy), DaMarcus Beasley (Houston Dynamo), Waylon Francis (Columbus Crew), Laurent Ciman (Montreal Impact), Chad Marshall (Seattle Sounders), Drew Moor (Colorado Rapids), Tony Beltran (Real Salt Lake).
MIDFIELDERS: Kaka (Orlando City SC), Ethan Finlay (Columbus Crew), Benny Feilhaber (Sporting KC), Graham Zusi (Sporting KC), Juninho (LA Galaxy), Dax McCarty (New York Red Bulls), Fabian Castillo (FC Dallas), Sam Cronin (Colorado Rapids).
FORWARDS: Clint Dempsey (Seattle Sounders), David Villa (New York City FC), Gyasi Zardes (LA Galaxy), Sebastian Giovinco (Toronto FC), Kei Kamara (Columbus Crew).