Hunky beefcake who claims he bedded KOURTNEY KARDASHIAN 9 months before birth of her son wants a court to order a DNA TEST!

Michael Girgenti, a male model is claiming to have had sex with Kourtney nine months before the birth of her son Mason, is suing the eldest of the three Kardashian sisters in Los Angeles for joint custody of the now-3-year-old boy, claiming to be the child’s father.

Girgenti claims he had “unprotected vaginal sex” with her in March 2009 at his Glendale, Calif. apartment — at the climax of which he “ejaculated inside [her] vagina” — in court docs filed Thursday, according to reports.

RadarOnline reports the stunning suit again calls into question if Kourt’s partner Scott Disick is truly Mason’s dad. Girgenti has petitioned the court for a DNA test of himself, Mason and Scott.

The Italian-Greek stud muffin, from Chicago, Ill., testified that he met Kourtney in Apr. 2008 at a photo shoot for 944 magazine, during a time period in which she and Scot were on “the outs”

Girgenti said they would often keep in touch via text — at one point, he said that she told him she “she wanted to hang” — and the meeting culminated in the hook-up he claims produced the child, as Mason was born on Dec. 14, 2009.

Girgenti said in court docs that Kourtney’s daughter Penelope, who was born last year,bears no resemblance to further justifying his statements.

Meanwhile, Kourtney’s  lawyer Shawn Holley countercharged, saying Girgenti is making “false and defamatory” accusations against her client.