Jacques Snyman scored a century before lunch for the Knights, who are in control of their match against the Warriors.
Snyman was excellent, smashing 109 which included 18 fours and two sixes. He was supported by opening partner Matthew Kleinveldt (73), as the pair shared a 164-run stand.
Raynard van Tonder (85), Pite van Biljon (53) and Farsan Berhardien (67*) helped the Knights to an imposing 405-5 at the close of play.
The Warriors were, however, forced to withdraw six members of their squad after two players tested positive for coronavirus and four others were in direct contact with them.
In Cape Town, the Cobras declared their first innings against the Titans on 264-9. Proteas Test opener Pieter Malan scored 51, while George Linde chipped in with 43 down the order. There were notable contributions from Zubayr Hamsa (32) and Kyle Verreynne (39). Lizard Williams was the pick of the Titans bowlers, returning figures of 4-51.
The Titans were 4-1 at the close of play, Proteas opener Aiden Markram out for just two.
In a rain-affected start in Durban, the Lions batted first and were 153-3 at stumps. Reeza Hendricks scored 76, while Temba Bavuma is 30* going into day two.