Khan, 24, seems to be on the verge of superstardom after rebounding from a shock 54-second knockout loss to the unheralded Colombian Breidis Prescott in Britain less than three years ago. But, after two big wins in America last year, Khan must now beat the 33-year-old Judah if he is to move closer to a possible showdown with Floyd Mayweather Jr, who returns to the ring in the fall.
After the anti-climax against McCloskey, Khan wanted to face rival champion Timothy Bradley next, but the WBC-WBO titleholder backed out, despite being offered additional money.
So instead, Khan defends his WBA title against the resurgent Judah, who recently recaptured the IBF championship after a 10-year gap. It is a more appealing fight for the fans and one that will undoubtedly provoke a comparison with Mayweather, who scored a one-sided unanimous decision over Judah five years ago.
Khan, 25-1 (17), is the favorite, but Judah, 41-6 (28), 2NC, will be coming to win. It is a hometown fight for the former undisputed welterweight champion, who was born in Brooklyn, but now lives and trains in Vegas.
Judah's trainer, the former four-division world champion Pernell Whitaker, says his man is planning to "crush" Khan and "put on a show" in his 18th world title fight.
Whitaker said: "He's mentally focused. He's more mature than ever before. All those things that happened in his past, that's over with. All you got to do is pick up what you saw last March and picture it being better."
Whitaker is referring to the seventh-round victory over South African Kaizer Mabuza in Newark, in which Judah got off the floor to regain the IBF belt he first won in 2000.
Khan's manager, Asif Vali, knows Judah will be no pushover. "It's a big fight for Amir and it's a hurdle he wants to get over," Vali said. "He wants two belts."
Roach, who also coaches Filipino icon Manny Pacquiao, said that Khan had enjoyed his best-ever training camp.
He added: "Zab has experience. He sets traps. We know when, where and why he does it - and we have an answer for all three. I have the younger, fresher guy who will dominate the older guy."
But Judah has been stopped just twice and lost only once at 140 pounds - a controversial second-round defeat against Kostya Tszyu nearly 10 years ago, which Judah bitterly disputed.
Although Khan's biggest weapon is his speed, Whitaker countered: "I don't know if there's anybody in boxing faster than Zab. I don't worry about the other guy's speed. Zab's got great upper body movement. He can make them punches miss. I'm just curious as to how he is gonna stop Zab from using his speed against him.
"Zab is 33 years old. He's in his prime. It's his time. I think the next three or four years, the way he's boxing right now, he'll be on top. We plan to go out there and put on a show and make the fight as easy as we possibly can."
Larry Merchant, the longtime HBO analyst, says Judah will be dangerous in the early rounds, but believes he is now more of a boxer-puncher than he was earlier in his career.
"Khan is the younger, quicker fighter," Merchant said. "When a fighter who used to be considered quicker than most of his opponents gets a little older, and fights a fighter who's quicker than himself, it turns the equation round. Unless there's a punch or two that changes the fight, Khan would seem to have the advantage."
Merchant said Khan's mindset in the fight would be decided largely by Judah's approach. "If Judah should find that he can't really catch up to this guy, or he's too fast-handed, and decides to survive, the fight becomes one Khan just wins."
"If he should just win, it's a win and he'll have more opportunities to look great. But I have a sense that Judah's reputation is greater than his actual ability right now, and he's been marketed because his name has been out there for a long time."