Bobk, thanks for your detailed explanation! I understand!
A couple more phrases.
He was pushed all the way but won in a tight finish.
He was challenged throughout the race by his opponent(s) but won by a small margin.
not a teacher
Yanx, your thanks are appreciated, but you don't need to send them in a separate post or to quote our replies back to us.
We are all happy to accept a simple click on the Like button as your acknowledgement of our help.
An extremely close race where it is impossible to tell who won simply by the naked eye, is a "photo-finish". A camera on the finish line takes a rapid series of images (currently 3000 images per second) as people cross the line and is then inspected in detail to see exactly which person crossed the line first.
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.
On the other hand, a synonym for 'cruise to victory' is 'win at a canter'. A canter is faster than a trot but slower than a gallop; so if you win at a canter you win without much effort - 'without breaking [a] sweat'.