KATE HUDSON's rumoured relationship with baseball star ALEX RODRIGUEZ is heating up - the New York Yankees ace has been introducing the actress to his best friends.

The Hollywood star has been linked to MADONNA's rumoured ex-Rodriguez for the last few weeks and has been spotted in the audience cheering the sportsman on during recent Yankees games.

Insiders claim the couple is taking steps towards making its romance public - and Hudson has even introduced A-Rod to her five-year-old son, Ryder.

A source spilled: "It's somewhat serious. He introduced her to a bunch of his friends."

Rodriguez was previously alleged to be dating MADONNA following her divorce from director GUY RITCHIE, while Kate, who shares RYDER with ex-husband CHRIS ROBINSON, recently split from on/off lover OWEN WILSON.