The superstar forward completed part of the session with the main group as he stepped up his recovery from the adductor injury he suffered in the 2-1 LaLiga win over Villarreal last Tuesday.
Messi, 32, was making his first start of the campaign when he sustained the adductor issue, having been troubled by a calf problem during pre-season.
Barca's goalless Champions League draw away to Borussia Dortmund on September 17 marked his return to action and the Argentina international could be available again for the club's second Group F game, at home to Antonio Conte's in-form Inter on Wednesday.
It could be a double fitness boost for Ernesto Valverde, with Ousmane Dembele also involved in the first session of the week.
Like Messi, the winger missed the trip to Getafe because of a thigh problem.
Two successive victories have lifted the Spanish champions to fourth in LaLiga and eased the pressure on head coach Valverde following an indifferent start to the season.