SANTA CLARA -- British Olympic discus thrower Lawrence Okoye's first experience playing football will be with the 49ers.

Immediately after the NFL's three-day draft concluded, Okoye announced Saturday on Twitter that he's coming to the 49ers as an undrafted free agent.

"Inadequate was my first impression standing next to him," coach Jim Harbaugh said of Okoye's April 10 visit to the 49ers. "This is an Adonis, just a great, physical specimen. Our creator created a beautiful man."

Okoye (6-foot-6, 305 pounds) finished last in the discus at last summer's London Games. The 21-year-old visited with the 49ers and the Saints before the draft, and he attended two of the NFL's regional combines.

"The things that really impressed: He had the rugby background growing up and didn't starting throwing the discuss until he was 18, and two years later he's throwing it in the Olympics," Harbaugh said. "You maybe start to put the pieces together and say, 'Taking on football at this time in his life?' I can see this guy doing it. I'm excited."

So is Okoye, who tweeted: "Proud to announce that I will be signing with the San Francisco@49ers!!!!!!!!!!!!!"

Other undrafted players believed to be joining the 49ers: Azusa Pacific offensive tackle Luke Marquardt, Minnesota running back Marqueis Gray, Texas State defensive back Darryl Morris, Wyoming defensive tackle Mike Purcell and Michigan offensive lineman Patrick Omameh.