Frankie Dettori got off the mark for the week as The Wow Signal justified his tall reputation in the Coventry Stakes at Royal Ascot.

The John Quinn-trained colt is by Australian horse Starspangledbanner who emulated his own sire Choisir when he won the Golden Jubilee Stakes at the Royal meeting.

Sent off the well-supported 5-1 equal favourite, The Wow Signal got off to a fast start and raced close to the pace.

Dettori coaxed his mount into the lead heading inside the final two furlongs (400m) and his rivals were unable to keep tabs on him as he galloped to the line to take the Group Two prize by 1-3/4 lengths.

Cappella Sansevero changed ownership at Monday's Goffs London Sale for STG1.3 million ($A2.37 million) and went some way to repaying his price tag when second in the colours of Qatar Racing.

The Wow Signal's victory was the second of the afternoon for Sheikh Joaan Al Thani's Al Shaqab Racing team, following the opening race triumph of Toronado in the Queen Anne Stakes.

"It feels great. It's been a few years since my last winner here, but I'm getting close to 50 now," Dettori said.

"I was worried about the ground being a bit quick but he showed tremendous courage, he's a real good two-year-old.

"I love Ascot and this is what it is all about, riding winners on the big day."