“It’s going to be a lot of hard work,” Duminy said after close of play on the second day.
“The wicket is pretty flat for the seamers, but there is a little bit there for the spinners. The game will probably speed up on day four and five so tomorrow is going to be a crucial day to set up those last two days.
“There is still a lot of hard to be done, there might still be an opportunity for a job with the ball so there are still three big days to come.”
Duminy scored an unbeaten hundred which led a spirited lower-order fightback. The Proteas find themselves with a commanding first innings total of 455-9 declared.
Duminy anchored key partnerships of 75 with Vernon Philander and 66 with Morne Morkel that weakened Sri Lanka’s attack.
“The biggest challenge was the spinners. Trying to marshal the partnership as best as possible, especially with Morne,” Duminy added.
“Vernon and I have played together a long time so we sort of understand each other’s games. Marshalling that partnership with Morne was crucial, and to see how he applied himself today was exceptional.”
The lower-order contributed 187 runs to the overnight total, sending the visitors into the drivers seat.
Having come into his own of late, Duminy is relishing his role at number seven.
“It’s always pleasing to get to three figures in these conditions,” he said.
“The hundred will come if I bat as long as possible, so I’m pretty pleased with getting the ton here today.”