Greg Mail has delivered the runs but he believes Stuart MacGill can deliver victory for NSW over South Australia in its Pura Cup match at the Sydney Cricket Ground.

With two full days to play, NSW lead by 451 runs after finishing the second day at 9-415.

Mail was unbeaten on 142 - his second first class century - anchoring a Blues attack which smashed 399 runs in the day.

It was a remarkable turnaround from the first day when 20 wickets fell as NSW made 188 and the Redbacks replied with 142.

Mail expected captain Shane Lee would declare in the morning, depriving the opener of being the first from NSW to carry his bat since Alan Turner 32 years ago.

"I'd hope 450 will be enough runs," Mail said.

"The pitch is starting to crack up a little bit and there's some variable bounce.

"Peter McIntyre was turning the ball quite a bit today and I'm sure Stuart will turn it a lot - he can turn it on anything."

NSW resumed this morning with Mail on one and Michael Slater on 15. Throughout the day, Mail focused on building partnerships with some of his more illustrious team-mates.

"The plan was for me to bat for a long time and to have other guys score runs around me.

"A lot of our guys score quickly and pile on the shots - I just try to play to my limitations."

The tall 23-year-old formed significant partnerships with Slater (49), Mark Waugh (51), Mark Higgs (53) and MacGill (53). In each of those stands, Mail played the steady hand while his team-mates blazed quick half-centuries.

And no half-century was faster than MacGill's. He brought up his 50 off 26 balls, with seven fours and a six over midwicket off Darren Lehmann.

In terms of time - 29 minutes- it was the equal second-fastest half-century on record for NSW.

Tibby Cotter took 18 minutes to score 50 in 1911-12 while the great Victor Trumper also took 29 minutes to reach the mark in 1905-06. No record of balls was available for those players.

It was a wonderfully improvised knock by MacGill, who really had just one shot - an unorthodox swat which he could hit anywhere in the arc from cover-point to midwicket.

"I saw he was up there with Victor Trumper - no doubt we'll be hearing about that for a while," Mail said of his brash batting partner.

In contrast, Mail took 202 minutes to bring up his half-century while his ton came up in a shade under five hours off 241 balls.

His innings wasn't without its mistakes - he survived a strong lbw appeal from Mark Harrity early in the day - but his edges all flew safely.

He showed great concentration and judicial shot selection mixed with compact defence against an attack which struggled to create chances.

He batted for 395 minutes and faced 299 balls, hitting 16 fours.

Part-time spinner Lehmann was the leading wicket-taker for SA, with 3-42.

© 2001 AAP