Newcastle midfielder Guimaraes, who was celebrating his 25th birthday, left the pitch for several minutes to receive medical attention after Rodrygo stepped on his right foot.
He returned to the session limping and looking uncomfortable, but completed it with his teammates.
Telles received a rough tackle from behind by Neymar and also needed medical assistance. Brazil coach Tite ordered the practice match to stop for a few moments, before Telles returned to the action.
Brazil's technical staff previously stressed that they wanted to assess the physical condition of the players when they reported for international duty on Monday.
After two days of light training at the Juventus facilities, where Brazil are holding a five-day camp before flying to Qatar on Saturday, Tite ran his first full session with all the 26 players in his World Cup squad taking part.
Defender Marquinhos, who missed training on Tuesday with an undisclosed injury that also ruled him out of Paris Saint-Germain's 5-0 win over Auxerre on Sunday, joined his teammates for the second half of the session.
Brazil decided not to play a friendly as part of their preparations for the tournament, which starts on Sunday, and they have more training sessions planned on Thursday and Friday before heading to Doha.
They begin their Group G campaign against Serbia on November 24 before facing Switzerland and Cameroon.
Additional reporting by Reuters.