Cruz Hewitt hasn't quite made the same grand entrance to tennis as his former world No. 1 father, crashing out in the first round of the Australian Open boys' singles.

Twenty-seven years after Hewitt famously became the youngest qualifier to make the Open main draw at just 15, Cruz suffered a 6-2 6-3 loss to American Alexander Razeghi at the same age.

Sporting a backwards cap and a two-handed backhand strikingly similar to his former world No.1 old man, Cruz looked a dead ringer for Hewitt on Show Court 3 at Melbourne Park on Sunday.

Cruz Hewitt, son of former world No. 1, Australia's Lleyton. Darrian Traynor/Getty Images

Despite the defeat, Lleyton Hewitt said he was "unbelievably proud" about Cruz's Open appearance.

"He's still very young. This is all a learning experience," Hewitt told Channel Nine.

"They asked me late last night if I would go out and warm him up this morning on Show Court 3. Just a really special moment.

"My first-ever main draw match at the Australian Open was actually out on Show Court 3 as well.

"Just some great memories coming back of me playing here. He's been around the traps, but he's worked extremely hard to get this opportunity. He is playing well."

The 15-year-old declined to speak to media after the straight-sets defeat.