Yet another winner at the July meeting for trainer Richard Hannon, the King Power Racing-owned colt had won at Haydock on his debut over seven furlongs on his only previous start to date.
Niggled along by Oisin Murphy to get closer at halfway, he began to look a big threat as the field panned out.
When the fancied pair of King's Command and Aidan O'Brien's Year Of The Tiger dropped away, Juan Elcano was the only one still on the bridle.
On meeting the rising ground, Mystery Power (7-1) went into overdrive and Juan Elcano, also having just his second outing, had no answer.
The winner pulled a length clear, with Maxi Boy back in third and Ropey Guest in fourth.
Speaking from Ascot, Hannon said: "He is a lovely colt and it didn't surprise us when he won first time out, but we have taken our time with him.
"Getting racing from a long way (out) would have probably helped him a bit. He won well and is a proper horse.
"He is a very straightforward horse, he has proved that again and is a horse that we have always liked.
"Seven furlongs is clearly no problem for him, but a mile is what he will want. I seem to have a lot of seven-furlong two-year-olds as opposed to the fast fireballs. We have some lovely juveniles and they are coming along nicely.
"We will now have to look at races like the Vintage and the Dewhurst and we will be giving him some more entries now."
Murphy added: "He is a super little horse. I felt James (Doyle on King's Command) controlled the race in the centre of the track and I was happy just to get a little tow and keep it pretty simple.
"I liked him. He is very tough and professional and at this stage you have to be pleased. He clearly got seven really well and he hit the line strongly."
Kevin Ryan said of Juan Elcano: "The ground was no problem, he just ran a little bit green into the dip and he got a little unbalanced and Andrea (Atzeni) just had to wait for him to find his stride again.
"The winner had gone, but he has finished out the race really well. He is a lovely horse for the future. There are no immediate plans. I will speak to the owner then make a plan."