Forgive Caroline Wozniacki, but she just can't help herself.

As former fiancée Rory McIlroy was charging back into contention at the US Open golf tournament on Sunday, Wozniacki tweeted her support for a McIlroy rival, USA TODAY Sports, For the Win reported.

Tweet.

Caroline Wozniacki congratulates Rory McIlroy rival Jordan Spieth for winning the Masters

Granted, support swelled for Jason Day the last two rounds at Chambers Bay as he battled his way to the top of the leader board heading into Sunday's final round.

But Day shot a 4-over 74 and finished at even-par 280 for the event, five shots behind winner Jordan Spieth.

Caroline Wozniacki's coach/father not mobile-tech savvy

Ironically, Day finished tied with McIlroy, who shot a 4-under 66 to pull himself to even for the tournament. McIlroy had gotten to 6 under for the round and 2 under for the tournament through the first 13 holes on Sunday before finally cooling off.

Wozniacki now has tweeted her support for a McIlroy rival during both of the PGA's major tournaments in 2015. She sent a congratulatory tweet to Jordan Spieth after he won the Masters in April, an event in which McIlroy was attempting to complete his career Grand Slam - winning all four PGA major events.

Wozniacki had not sent a congratulatory to Spieth as of Sunday night for winning his second straight major.

McIlroy and Wozniacki were to be married sometime late in 2014 after the two had become engaged on New Year's Eve in 2013. Just after wedding invitations were sent, McIlroy reportedly got cold feet and called off the engagement.

He broke the news to Wozniacki over the phone. The athletic seasons of each took off after the breakup. McIlroy won the British Open and the PGA Championship - the last two majors of 2014. Wozniacki advanced to the US Open women's tennis finals and the season-ending WTA finals as she moved up to No. 5 in the world.

Wozniacki now apparently is romantically involved with Houston Texans defensive end JJ Watt, while McIlroy recently confirmed a relationship with Erica Stoll.

It will be interesting to watch Wozniacki's Twitter account when McIlroy attempts to defend his British Open crown next month.