Morne Morkel may have charged through Pakistan's lower-order to finish with 5 for 54 but he insists he's 'only firing at 75%' and warned that he has plenty more to offer after South Africa took control of the first Test in Dubai.

Morkel had a productive one-day series but was below his best on the second day here as Pakistan scrapped hard to reach 144 for 2. Yet after a firm word from his captain Graeme Smith on the morning of the third day, Morkel found his range with the second new ball, finishing off what Johan Botha's three wickets started to roll Pakistan out for 248, a collapse of 8 for 72.

"Yesterday the idea was to get the ball in the right areas and be aggressive with the new ball but we weren't really on the mark," he told reporters. "Graeme [Smith] sat us down this morning, we set high standards for ourselves as a bowling unit and I'm just happy and pleased that things paid off."

Morkel roughed up the lower order with some short stuff on his way to his third five-wicket haul but was happy to acknowledge the role played by his fellow bowlers. "I can't take all of the credit. The whole bowling unit today bowled really well. Johan (Botha) and Paul (Harris) were good yesterday as well. Dale (Steyn) could easily picked up a few wickets. I was lucky that things happened for me. The guys created the pressure from both ends."

South Africa's top order combined to extend the lead to 271 and with Hashim Amla and Jacques Kallis looking set to bat on for a long while yet Morkel has plenty of time to prepare for the final innings. He is now just three short of 100 Test wickets but so far only 33 of his scalps have come in the second half of the game. It could help to explain why South Africa were twice denied by England in their last home series when, at Centurion and Cape Town, the tourists survived nine-wickets down to draw the games.

This time Morkel insists he's prepared for the challenge and thinks he can get better. "I still think I'm only firing at 75%. I think I've got some more left in the tank and can improve. But I'm happy with today because as a fast bowler you need confidence and rhythm and this five-for is something I can move forward on.

"I was preparing myself mentally to bowl in the second innings from this afternoon itself. I've played in a couple of Test matches like the one against England where bowling in the second innings has been a mental challenge. We'll come up with a game plan tomorrow morning."