Their tweets included a photo of fireworks above the Sydney harbor and, of course, a shot of the ring.
McIlroy, 24, from Northern Ireland, had a disappointing 2013 season on tour after leading the PGA in earnings in 2012. At one point in mid-October, he was rumored to have split with Wozniacki, but squashed those rumblings when he called the 23-year-old Dane "my girl" after winning the Luxembourg Open in late October. He capped the year by beating Adam Scott by one stroke to win the Australian Open on Dec. 1.
Wozniacki, who withdrew from the Brisbane International tournament this week because of a shoulder injury, is also trying to shake off a rough 2013 season, when she won only one tournament. She failed to get past the fourth round in any major.