|Fourth Investec Test, Old Trafford, day three|
|England 362 & 224-8 (66.2 overs): Moeen 67*, Root 49, Olivier 3-38|
|South Africa 226 (72.1 overs): Bavuma 46, Anderson 4-38|
|England lead by 360 runs|
Moeen Ali should stay batting at number eight for England, according to former captain Michael Vaughan.
With England struggling to fill gaps in their top order, Moeen hit an unbeaten 67 to push their lead over South Africa to 360 on day three of the fourth Test.
"They need a number two and a number five, but keep Moeen at eight," said Vaughan.
"He is a wonderful player and I like him in that position - I like the batting line-up being deep."
The left-hander, who has five Test hundreds, has batted in every position from one to nine for England.
Earlier in this series he was batting at number seven, but has been shifted down a place as the hosts looked to strengthen their line-up.
He forms a strong lower-middle order alongside Ben Stokes and Jonny Bairstow, with Chris Woakes set to return from a side injury for the three-Test series against West Indies.
"With all the power in Stokes, Bairstow, Ali, Woakes, I wonder why do we have to have a set order?" added Vaughan on Test Match Special.
"Why can't we go into a new era of Test cricket and say 'the top five are set, but six downwards, we'll juggle it about'?
"For example, on a day where right-handers are more use, we'll send one of those in."
Moeen Ali Test record by batting position
Moeen's 59-ball knock, which included three sixes, steadied England from a position in which they were vulnerable to a South Africa resurgence.
At 153-7, the home side led the Proteas by 289, only for Moeen to counter-attack.
"It's one of my best innings for England in terms of trying to take the momentum and putting pressure back on the opposition," said Moeen.
"It was good fun, the situation needed some momentum and I backed myself and went for it."
Moeen's knock took him past 200 runs for the series and, coupled with his 20 wickets, the Worcestershire man is the first to do such a double since Andrew Flintoff in the 2005 Ashes.
His success comes after some confusion over his role at the beginning of the series.
In including Hampshire's Liam Dawson for the first two Tests, England coach Trevor Bayliss called Moeen the "number two spinner".
"That was the worst bit of PR this England team has done," said former England off-spinner Graeme Swann.
"Moeen is the best spinner in the country, but the fact they did that shows what he feels about his bowling. They haven't worked out how to get him to believe in himself properly.
"He needs someone to get in his head and tell him how good he is with the ball."