Miko de Beauchene edged out last year's winner Halcon Genelardais in the run-in to win the Welsh National at Chepstow.
Miko de Beauchene finished strongly to claim victory at Chepstow
The pair pulled clear of the rest of the field with three fences to go but Andrew Thornton urged his mount into one final effort to get to the line.
Halcon Generlardais and Christian Williams dug deep but fell short.
It proved an emotional victory as Miko de Beauchane's trainer Robert Alner is recovering in hospital following a car accident last month.
The David Pipe-trained Over The Creek stayed on well for third, just ahead of early pacesetter Naunton Brook.
Gungadu, trained by Paul Nicholls and ridden by Ruby Walsh was sent off the 4-1 favourite and held every chance with half a mile to go along but faded in the finish.
Not Left Yet was also well fancied but he parted company with Timmy Murphy in front of the stands with a circuit to run.
Halcon Generladais looked to have stolen the race with a super leap over the second last but carrying top weight of 11st 12lb eventually told with the winner triumphing by a head.
Thornton told BBC Sport: "What can you say? The horse is very gutsy and very tough. And just like his trainer, very genuine.
"We all wish Robert could have been here saddling the horse up but there is no better tonic for him than this.
"Coming up to the last I thought I had one more roll of the dice to get his nose in front and he just kept on going for me.
"I was never confident that I had won so I was very happy when I heard the result."
Sally Alner, wife of the winning handler, added: "That was unbelievable and I just hope Robert saw it."
Meanwhile, odds-on favourite Voy Por Ustedes claimed an easy victory in the Desert Orchid Chase at Kempton.
Alan King's charge, ridden by Robert Thornton, pulled clear of his only challenger Hoo La Baloo at the third last and dominated after that for his second consecutive win in the race.
Coral Welsh National (Chepstow)
1. Miko de Beauchene (A Thornton) 13-2
2. Halcon Genelardais (Christian Williams) 17-2
3. Over The Creek (J W Farrelly) 10-1
4. Naunton Brook (David England) 33-1
Desert Orchid Chase (Kempton)
1. Voy Por Ustedes (R Thornton) 2-5 Fav
2. Hoo La Baloo (S Thomas) 4-1
3. Mister Quasimodo (J Tizzard) 10-1