South Africa A 325 for 5 (Petersen 111*, Anderson 3-41) drew with England 456 for 7 dec. (Pope 132, Denly 103, Burns 56)

Joe Root says that England will be relying on "trust either way" as they weigh up the pros and cons of playing Stuart Broad, Jofra Archer and Jack Leach in this week's Boxing Day Test at Durban, despite all three of them missing the warm-up phase of the tour due to illness.

The trio were unable to take part in the final day of England's second practice match at Benoni - which had been downgraded to a friendly to give them a chance of taking part - but did at least spend a second afternoon in the nets as they begin to recover their match fitness with the first Test now just four days away.

In their absence, England were given a stiff work-out by the South Africa A batsman Keegan Petersen, whose hard-earned century formed the basis of their total of 325 for 5. The match was called off as a draw shortly after his dismissal for 111, with England declining the chance to give Craig Overton and Dom Bess - the squad's newly arrived reinforcements - a chance to stretch their legs in the final session of the match.

Root admitted he had been taken by surprise when the teams shook hands in the middle before the scheduled tea break, but insisted that England's preparations had been "as good as can be" in the circumstances. "We've managed the illness as best we can. And in terms of the two games, we've got a huge amount out of them," he said.

The biggest positives revolved around the batting form of Joe Denly and Ollie Pope, both of whom made their first centuries for England in posting 456 for 7 declared in the first innings, and the successful return to action of James Anderson, who bowled with control and some penetration to claim 3 for 41 in 19 overs, his first proper work-out since aggravating a calf injury during the Ashes in August.

"We had two guys making hundreds and getting to 450, which is becoming a habit in terms of the mindset and process," said Root. "And there was Jimmy coming back and playing as he did, hitting his straps really well."

Anderson, 37, had missed England's tour of New Zealand while undergoing intensive fitness work at Manchester City's Etihad Stadium, and he also arrived in South Africa early to acclimatise at England's pace-bowling camp in Potchefstroom. And Root believed that the benefits of his preparation were clear, not just in his display during the match, but in the example it set.

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"You can see the benefit of his time off," said Root. "He's worked really hard physically and looks in great shape, probably as strong as we've seen him. And it showed in his performance. It's really pleasing and a great example to the rest of the guys, at the age he is, to still have the desire and hunger to take that time, improve himself and come back and perform like that."

However, given that Anderson broke down after just four overs of his last Test, against Australia at Edgbaston, there are clear concerns about over-burdening him should he play in the Centurion Test, particularly if Broad and Archer are still feeling their own way back to full strength.

Root, however, was adamant that the bowlers themselves - and Broad in particular as the senior player among the ill trio - would play a key role in assessing their ability to take the strain of a five-day match.

"He's got more experience of getting through games and managing his body," said Root of Broad. "He's been quite savvy when he's had niggles in a Test match or not felt 100 percent. It's very rare that guys go into a game carrying an illness, and so he'll be making an honest call about whether he can get through five days.

"If he's as close to 100 percent as possible, he'll tell us, and if not, a big part of it is that you don't want to let the rest of the guys down, and say that you're fit to play when you are not, and end up pulling up and putting a workload on the rest of the team.

"It'll be a fine balance, there will be a bit of trust either way in making sure the right decision is made, but we'll do absolutely everything we can to get those guys ready to go. It's not ideal, but these things happen in Test cricket and we have to get on with it."

England's squad has now swollen to 19 players with the arrival of Overton and Bess, and although that does also include Mark Wood, who is not expected to be ready for action before the New Year, Root said that the abundance of bowling options could allow England to take a staggered approach to the two festive Tests, with some of the returning players held back until the second Test in Cape Town on January 3.

"The beauty of the squad we've got here is the variety of the attack and the number of different options we can go to," said Root. "The reason we brought the amount of guys out was to be ready for each Test match, and if it means we can play a different side then we are in a position to do that, whether it's through fitness or illness, or just a selection thing."

Root didn't rule out the possibility of going into the Boxing Day Test with no specialist spinner - just as England did in their most recent Test, against New Zealand in Hamilton last month.

"It's certainly an option, but it's not necessarily the way we'll go." he said. "We'll look at the conditions, see how the wicket deteriorates over the course of the week, and put all that together and make a smart decision."