Drake is not only a passionate Toronto Raptors fan, he is also the team's global ambassador. While this is a very loose title, Drake mentioning Lou Williams in his song "6 Man" could count as one of his duties as an ambassador. 

Boomin' out in South Gwinnett like Lou Will

6 man like Lou Will, 2 girls and they get along like I'm... (Louuuu)

Like I'm Lou Will, I just got the new deal

Williams seems to be a popular muse for the rapper as he also appears in a commercial for Drake's clothing line colloboration with the Raptors. In the ad, Williams is wearing the new line of clothing while shooting around at the Air Canada Centre. 

It makes sense that Drake will put Williams in the commercial. The two have developed a close relationship and Williams even wore Drake's "OVO" Jordan 10 sneakers for the Raptor's Drake Night back in December. 

First getting mentioned in song and then appearing in a commercial. The next logical step for Williams is to rap in Drake's next music video.