Australia trail by 170 runs after South Africa enforce follow-on
Travis Head leads with 87 not out as Australia finish day four at 156-4 in their second innings, still trailing South Africa by 170 runs after being forced to follow on.

Travis Head led a defiant rearguard with an unbeaten 87 as Australia finished day four at 156-4 in their second innings during the second Test against South Africa, still trailing by 170 runs. Head faced 138 deliveries and struck nine boundaries, joined by nightwatchman Scott Boland on 2 not out at stumps.
South Africa had earlier enforced the follow-on after Marco Jansen wreaked havoc with a stellar 5-33. The visitors were bundled out for just 99 runs in their first innings, conceding a massive 326-run lead in response to the Proteas' declaration at 425-9, anchored by skipper Temba Bavuma's career-best 179.
The collapse marked Australia's fourth-lowest innings total and the third-highest lead conceded in Tests against South Africa. Jansen ripped through the batting lineup, leaving Australia reeling at 69-6 by lunch on day four after four quick wickets in the morning session.
Jansen struck early when Boland was caught behind on the seventh ball of the day. Head fell lbw for 14 following a review, while Marnus Labuschagne departed for 14 after a superb gully catch by Simon Harmer off Anrich Nortje, reducing the tourists to 45-4.
Nortje was forced off the field due to a lower-body injury after bowling just 2.3 overs, leaving South Africa a bowler short. Though Matt Renshaw and Steve Smith resisted briefly, Jansen removed Renshaw and Alex Carey in the same over before lunch.
Post-lunch, Jansen completed his fifth Test five-wicket haul by dismissing Mitchell Starc. Smith top-scored in the first innings with 28 off 88 balls, though he took a painful blow to his helmet and did not bat in the second innings.
Despite Nortje's absence, South Africa enforced the follow-on and struck immediately when Kagoda Rabada removed Nic Maddinson for eight. Head and Labuschagne added 92 runs for the second wicket to steady the innings before Labuschagne fell to Harmer.
Rabada further dented the tourists by bowling Renshaw, while Head brought up his fifty off 81 balls. Beau Webster chipped in with 27 before falling lbw to Harmer just before the close of play.