Duncan sat out of the team's win Thursday over the Phoenix Suns, but returned to the lineup for Friday's 108-95 win over the Los Angeles Lakers.
It's unlikely that Duncan's knee issues are serious, as Spurs coach Gregg Popovich typically manages the minutes of his veterans to prevent any potential injuries from worsening. In Duncan's absence, it's expected that bench players such as Boris Diaw and Boban Marjanovic will receive extended minutes.
David West will likely replace Duncan in the starting lineup. In his 19th NBA season, Duncan, 39, has played in 37 games this season, averaging 8.9 points. The Warriors (40-4) own the NBA's best record, followed by the Spurs (38-6).
Spurs-Warriors who has the edge?
With the two top teams in the NBA squaring off tonight in Oakland, Brian Shaw gives the defending champs the edge.
Green on Duncan not playing: 'Not surprised'
Draymond Green reacts to the news that Tim Duncan won't play in Monday's game between the Spurs and Warriors due to soreness in his right knee.