Messi out for defending champions Inter Miami as Leagues Cup begins
The 37-year-old Argentine striker suffered a right ankle injury in his nation's victory over Colombia in the Copa America final this month.
Messi missed two MLS matches last week and Wednesday's MLS All-Star Game against Mexico's Liga MX All-Stars.
Martino said Messi remains in a walking boot as he works with club trainers but "the ankle is getting better and better," according to the Miami coach.
Last year, Messi arrived at Inter Miami and led the club on a title run in the inaugural edition of the Leagues Cup, which features MLS and Mexican clubs in a World Cup-style format.
There are 15 three-team groups in the first round and two from each will advance to the knockout stages along with the reigning league champions, Club America and the MLS Columbus Crew.
This year's opening matches were played Friday with host Orlando routing Montreal 4-1, DC United winning 6-5 on penalties after a 3-3 draw at Atlanta and 10-man host Austin edging Mexico's Pumas 3-2.
Icelandic midfielder Dagur Thorhallsson, Uruguay's Facundo Torres and Argentine striker Ramiro Enrique gave Orlando a 3-0 half-time lead and Argentina's Martin Ojeda added another goal in the 57th minute while Montreal's Josef Martinez, a Venezuelan midfielder, averted a shutout loss in the 69th.
Austin goalkeeper Stefan Cleveland denied a penalty shot by Pumas striker Guillermo Martinez in the fourth minute of second-half stoppage time as the Texas club hung on after Osman Bukari's red card in the 34th minute with Austin up 1-0 on Alexander Ring's eighth-minute goal.
Gyasi Zardes and Sebastian Driussi added goals for Austin while Martinez and Ali Avila scored for Pumas to set up the thrilling finish.
DC United's scheduled home match against Santos Laguna next Wednesday at Audi Field was moved to the home stadium of the Philadelphia Union - Subaru Park in Chester, Pennsylvania - due to concerns over field conditions in Washington.
Leagues Cup organizers fined DC United an undisclosed sum over conditions, with the club saying it is installing a new grass field at the stadium on July 31, a move that had been previously planned for August 1.
