Joe Root, Joe Denly and Dom Sibley posted half-centuries to open England' s tour of South Africa with a first-day score of 309 for 4 against a Cricket South Africa Invitational XI in Benoni.

Root backed up his previous innings of 226 in the second Test against New Zealand a fortnight ago by top scoring for England with 72 off 86 balls on day one of two at Willowmoore Park before he retired not out. With Denly and Sibley also retiring not out after reaching 60 and 58 respectively, England were effectively seven wickets down at stumps as Zak Crawley closed unbeaten on 28 accompanied by Sam Curran, who was not out 18.

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England will bowl on Wednesday, when they hope to have the services of Jofra Archer and Stuart Broad, who were feeling unwell on Tuesday.

Rory Burns, Jos Buttler and Jonny Bairstow were out to soft dismissals in the teens on Tuesday, while Ollie Pope was out lbw for 20.

Denly made the most of surviving a dropped catch when he was on 28 and Sibley showed no ill effects after being struck on the helmet towards the end of his innings, which lasted more than three hours. The pair put on a 103-run stand, which Sibley thoroughly enjoyed, having not had the chance before after falling for 22, 12 and 4 while opening in his only three Test innings to date, on the recent tour of New Zealand.

"It's the first time I've batted with Joe," Sibley said. "I didn't make it long enough in New Zealand. We complement each other quite nicely."

Burns and Sibley put on a chanceless 37 runs in the first hour before Burns threw away his wicket, taking on left-arm seamer Stephan Tait and top-edging a hook to fine-leg.

Root set about scoring quickly and finished as he began, taking 16 runs off the final over he faced, including a last-ball slog-sweep for six.

"He played well, he's coming off a double hundred in New Zealand so he looks in good form, so hopefully he continues," said Sibley, who was content to come off after reaching his fifty despite not having had as much batting time as he would have liked during the two Tests he has played so far.

"It's all part of warm-up games, making sure everyone gets enough time in the middle," he said. "You can't really beat time at the crease so I was happy with the amount of time I got out there especially after having a couple of days in the nets."

Sibley's disappointing returns in the New Zealand Tests followed a century in a warm-up match and prompted him to spend time with Warwickshire batting coach Tony Frost and freelance consultant Gary Palmer making "little tweaks" to his technique before flying out to South Africa.

"Nothing major, just getting back to what I was doing well in the summer for Warwickshire and hitting past mid-on, which I did well today, so I was pleased with that," Sibley said. "I felt balanced, so that's good. I want to peak at the right times and hopefully that happens.

"I've only had three innings and I think especially in the first innings I felt good, I felt at home, and then in the second Test match I probably put myself under a little bit too much pressure to get a big score. I'm just going to play my game, stick to my strengths and be nice and chilled out there.

"I've got to start getting some scores and stuff but hopefully Boxing Day will be my day so hopefully I play."

Buttler was dropped at slip on just five but he offered a repeat chance to depart for 15 while Bairstow's return to England's red-ball side following his omission for the New Zealand Tests ended when he smacked a rank full toss to mid-on.

England will play one more tour match, a three-day fixture against South Africa A starting on Friday, before the first of four Tests starts on Boxing Day.