The 28-year-old was earlier forced to leave a training session at Brazil's Granja Comary base in Teresopolis, near Rio de Janeiro, to undergo physiotherapy.
Teenager Talles Magno, a key member of the Brazil team that won last year's under-17 World Cup, put Vasco ahead in the ninth minute at their Sao Januario stadium with an easy tap-in following Cayo Tenorio's cross.
Arias was taken off on a stretcher in the 12th minute of Friday's clash at Estadio Metropolitano after colliding with Darwin Marchis in an incident that left the Bayer Leverkusen player's left foot jutting sideways from his ankle.
"I also had a lot of days in my recovery when I wondered how I was going to play football again, but there were also good days that I'll never forget, such as starting to walk and it not hurting and then being able to run and in my first game back I scored after just 25 seconds."
"There needs to be some differences, but I am absolutely convinced that even under these circumstances, there will still be fantastic games. We will adapt, we will also be supported with the organizing committee in anything we need to do to make sure that athletics is the center stage of the Olympic Games."
The marathon is a two-day-event, with smaller distances reserved for Saturday, while the 42-km long main race started on Sunday at 9am local time.
Both players had also tested positive on Sunday, along with defender Christian Ramos and striker Aldair Rodriguez. The latter two were cleared to play in Tuesday's fixture at Estadio Nacional after testing negative on Monday, the Peruvian Football Federation said.
The Azzurri will take on Poland and the Netherlands on October 11 and 14. Enditem
The two-time world champions arrived in La Paz on Sunday and held a light training session on Monday at a training complex belonging to local first division team The Strongest. Enditem
Malian captain Hamari Traore secured the opening goal in the third minute while El Bilal Traore and Haidara Amadou also scored in the 49th and 75th minutes respectively to secure a convincing win for the Eagles.
In the 76th minute, Lyu Yueyun received a pass and rifled into the net, securing the 4-0 victory for Wuhan.