Spencer has no doubt the four-times capped player could handle life with the Old Firm and become the long-term successor to Artur Boruc, should Celtic ever decide to cash in on their highly-regarded Pole.
"Brad is the money," Spencer told the Daily Mail. "He would have no problem playing in the SPL right now.
"There's no doubt Brad can be the next big American goalkeeper to play in Europe. I've nothing against Brad Friedel or Tim Howard, but this guy is a great size and is a fantastic athlete, as well.
"He throws himself about, he's really brave and he already has some good international experience. He played really well in a game against Sweden last weekend and that clean sheet raised his profile further.
"No disrespect, but if you are performing well on the international stage, then I'm pretty sure you can handle playing in Scotland. Obviously, Celtic have Boruc in there and the question would be whether Brad could get enough game time to continue developing if he was to sign.
"But he definitely has the ability to go on and star at that level."