Landon Donovan has urged caution about the growing hype surrounding Cavan Sullivan, saying he's seen too many supposed future superstars in American soccer falter over the years.

Sullivan has been tipped as the next big thing in American soccer amid a meteoric rise this year with the Philadelphia Union and the U.S. men's national team.

Over the past weekend, Sullivan broke the MLS single-season record for goal contributions by a teenager (21), continuing a stellar campaign with the Union. Sullivan was recently voted the MLS Player of the Month for September, becoming the youngest player to earn the honor.

Sullivan's stock rose even higher in the recent international window, which saw him make his USMNT debut at age 16, then become the the youngest USMNT goalscorer ever at age 17 years, 5 days.

But Donovan, himself a formerly hyped teenager who made it big, has warned against anointing Sullivan just yet.

"I am measured and calm because I, unlike a lot of new soccer fans, have seen this story happen over and over," Donovan said on the Unfiltered Soccer podcast.

"I saw it with Freddy Adu. I saw it with a guy you won't even remember, Santino Quaranta. I saw it with Eddie Johnson. I saw it with Gio (Reyna) and seen how it's progressed. There will be the next superstar at some point. It might be Cavan. I'm hoping it's Cavan, or maybe it's Julian Hall."

One player who did live up to the massive hype has been Christian Pulisic, who previously held the record as the youngest USMNT goalscorer and has gone on to become one of the all-time greats of American men's soccer at age 28.

Donovan spotlighted Pulisic as a player who was the exception to the rule, saying he hopes that Sullivan can follow in Pulisic's footsteps.

"Christian was unique. Like he was a superstar (as a young player), and he became a superstar," Donovan said. "We watched it, but that is so rare. It is so much more often the case that we get all excited and hyped or whatever, and they have an OK career, but they're not a prominent national team player. And so if Cavan continues on this path, I will be on board. It's not that I don't want them to succeed, I've just seen this story over and over, and so I'm reticent to go crazy yet."