Scott Disick is sick and tired of the rumors making rounds that Kourtney Kardashian, 37 and Justin Bieber, 21, are hooking up and now, hes going all out to discredit his baby mamas new man.

READ: Kourtney Kardashian denies dating anyone, not even Scott Disick

On April 19, Scott wished his ex a happy birthday by posting a steamy throwback picture of the former couple sharing a passionate kiss in water while on vacation back in 2009. He captioned his post, "Happy birthday @kourtneykardash everyone who knows you loves you so much!"

The 37-year-old stunner - who split from Scott in July last year after a nine-year relationship - celebrated her birthday on Monday, April 18 in Iceland with her sister Kim Kardashian and her husband Kanye West.

Scott has been in Coachella with Kendall and Kylie Jenner. He was also seen with Amber Rose, who is best friends with Rob Kardashian's fiancée Blac Chyna.

READ: Scott Disick warns Justin Bieber "stay away from my kids"

But according to People magazine reports last week, Kourtney has still been seeing Justin Bieber 'on and off' for several months. The pair allegedly hook up whenever the 'Sorry' hit-maker is in Los Angeles.

Do you think Scott's sexy post was aslap on Bieber's face?