The Serbian came from a set down to defeat US Open conqueror Andy Murray 4-6 6-3 7-5, however his progress into the final four is yet to be guaranteed, with Berdych defeating Jo-Wilfried Tsonga 7-5 3-6 6-1.
Djokovic must now defeat Berdych or at least take a set off him in their next match on Friday to book his place in the semifinals.
“It was really important obviously for me to win this match today, as it was for Andy,” Djokovic said after defeating the Scot.
“But I will not try to depend on some other players’ scores and matches. I will try to focus and win every match that I play.”
On the gripping Murray contest, Djokovic added: “Another great match, another great performance from both of us.
“I didn’t expect anything other than a tough match that went down the wire and was decided in the last point.”