Smith batted defensively to reach his first Test ton since May 2005

Pakistan require an unlikely 349 more runs on the final day to avoid losing their Test series against South Africa.

Graeme Smith (133) and Jacques Kallis (107no) hit patient centuries before the tourists declared on 305-4 to set a world record target of 457 in Lahore.

Salman Butt edged Makhaya Ntini to slip early on but Kamran Akmal (49no) and Younus Khan (48no) dug in to add 93.

But the Proteas are still favourites to clinch a first subcontinent Test series win outside Bangladesh since 2000.

Pakistan were hampered by the absence of paceman Mohammad Asif, who will not bowl again in this game after injuring his elbow on Wednesday.

Kallis had a lucky escape on 47 when captain Shoaib Malik misjudged a lofted shot at long-off in left-arm spinner Abdur Rehman's first over.

But other than that there were few scares for the right-hander, whose previous three Test innings had yielded 155, 100 not out and 59, as he and Smith went on the defensive.

If we take two to three wickets in the morning we'll be able to run through them Graeme Smith

Smith was first to get to three figures, his first Test century since hitting 126 in May 2005 in Antigua, before top-edging a sweep off leg-spinner Kaneria having faced 296 balls.

After Kallis had nudged his way to his 27th Test ton off 231 deliveries, Ashwell Prince was bowled by a delivery from Rehman which turned sharply and the declaration was not long in coming.

Akmal and Younus survived most of the final session to give their team an outside chance of making history but Smith is confident his men will wrap things up on Friday.

"We are still in a strong position and the pressure is right on Pakistan," he said. "If we take two to three wickets in the morning we will be able to run through them."

Of his long overdue hundred, the skipper added: "It is something special to score my first Test century in the subcontinent.

"It was turning a lot more in the morning and the two spinners didn't give many bad balls. It was tough to find scoring options."

Butt said on Thursday: "There have been some decisions where we have been unlucky like, I think, myself in the second innings of the Karachi Test.