Creative Cause finished third in the $1 Million, Grade I Preakness Stakes and Zetterholm was fourth.
"On to New York, baby," winning trainer Doug O'Neill said after his Flower Alley colt got by pacesetting Bodemeister to win by a neck.
I'll Have Another must win the Belmont Stakes in New York June 9 to become the first Triple Crown winner since Affirmed in 1978.
Bodemeister jumped to the front right out of the gate in the 1 3/16-miles Preakness at Pimlico and set an uncontested and reasonable pace into the top of the stretch. At that point, jockey Mario Gutierrez had I'll Have Another rolling outside of rivals and set him down for the stretch run.
After a grinding stretch run, I'll Have Another just edged to the front in the final few jumps and won by a neck, finishing in 1:55.94.
I'll Have Another paid $8.40, $3.80 and $2.80. Bodemeister returned $3.20 and $2.80. Creative Cause paid $3.60. The $2 exacta with the two favorites in reverse order paid $18.60.
I'll Have Another, a Kentucky-bred son of Flower Alley, remains undefeated as a 3-year-old. He won the Robert B. Lewis Stakes and the Santa Anita Derby in California before his triumph in the Run for the Roses.
The Belmont has been a graveyard for Triple Crown hopes, however. Run at 1 1/2 miles over the sweeping Belmont Park main track, the race tests the conditioning of a horse in running three tough races in a five-week span, and his endurance over a distance unusually long by American standards.
In recent years the likes of Sunday Silence, Silver Charm, Real Quiet, Smarty Jones and Big Brown have fallen one "jewel" short of completing the difficult triple.