South Africa captain Graeme Smith is of the opinion that fast bowler Vernon Philander has room to improve, which is a scary prospect for opposition batsmen as he took nine wickets in the second Test against Pakistan.

While Dale Steyn is the number one ranked bowler in Tests, and bowls at 145kph most of the time, Philander is often in the shadows, despite being second in the world and taking nine five-fers in the 15 Tests he's played.

But Smith feels 'Big Vern' can be even more impressive, especially if his pace picks up. Philander has contended with a variety of injuries in recent months, and Smith hopes the paceman will be able to perform consistently in all his spells.

Smith said after the second Test win: "Vern has got the results but he is still a work in progress. I think he can get better. I think he himself would like to see his pace up a little bit.

"Outside of that his skill factor is immense. The seam action that he gets out of his hand... the questions he asks batters. It's great to stand at slip and watch that happen.

"If he can pick up a little bit of pace, which he has definitely got, his old ball spells will get even better.

"His new ball spells are so effective that if he can get his old ball spells to the same level he can really produce. I know it's asking a lot but I do believe he can get there."

Meanwhile, the Proteas will be without Morne Morkel for the third Test in Centurion on Friday as he picked up a hamstring injury, meaning Rory Kleinveldt is set to get a game.