Double European champion Mo Farah won the 5,000m at the UK Athletics trials for the World Championships - then announced he will only be competing in the 10,000m in Daegu, South Korea.
Farah clocked 14 minutes, 0.72 seconds to win the 5,000m for his ninth successive victory this season.
"I'm definitely going to concentrate on one event and that is the 10k," said the 28-year-old.
"I'm going out there believing I can win a medal."
Farah has improved swiftly since moving with his wife and daughter to Portland, United States to be coached by Alberto Salazar.
"I've made a lot of changes in my life, as an athlete you have to make sacrifices," he added.
"Things are going really well. The crowd gave massive support, which was nice.
"I've definitely got confidence and I believe everything is going well. I can't say I feel invincible, but I do feel I'm ready."
Aldershot athlete Andy Vernon followed Farah home in 14:01.72.
The top two athletes in each event at the UK Trials will guarantee their ticket to Daegu, provided they have the 'A' standard qualifying mark.
Farah's final race ahead of the World Championships, which begin on 27 August, will be at the Diamond League meet in London on 5-6 August, where he will run the 3,000m.
World bronze medallist Jenny Meadows won her first national outdoor crown in the 800m, finishing ahead of Emma Jackson and Marilyn Okoro in a time of 2:02.28.
"It's such a relief," Meadows told BBC Sport. "I've always wanted to win this title.
"It's amazing to get global medals but for me, it's still important to be UK champion so I'm really thrilled that I've managed to do it.
Martyn Rooney produced a season's best of 45.44 to claim victory in the 400m, ahead of Chris Clarke and Dai Greene.
However, the Croydon athlete's time wasn't good enough to achieve the 'A' standard (45.23) meaning no British athlete has yet to automatically qualify for Daegu.
After finishing second in Saturday's women's 100m, Anyika Onuora took the national title in the 200m in 23.26. Commonwealth silver medallist Abi Oyepitan followed in 23.57.
Christian Malcolm defended his national 200m title and secured his place in Daegu winning in 20.85. James Ellington took second place in 20.91.
Perri Shakes-Drayton looked strong in the women's 400m hurdles winning in 55.52.
The London athlete had already beat 400m Olympic champion Christine Ohuruogu to the national title in Saturday's competition.
"I've had a good weekend at the office," Shakes-Drayton said. "To come to these championships and run quality times, all the hard work I've put in over winter has paid off.
"It's given me the confidence to know I'm fit enough not to hold back and make it easier for the girls in the race."
World heptathlon champion Jessica Ennis produced a season's best of 6.44m in the long jump, just seven centimetres below her personal best, before throwing 42.93m in the javelin.
"I'm a little bit achy, but not too bad," Ennis told BBC Sport. "I'm pleased to jump a personal best in the long jump but a bit disappointed with the javelin. But all in all, it's been a good weekend."
Larry Achike, the 1998 Commonwealth Games champion, won the triple jump in Idowu's absence with a season's best leap of 16.83m.
In a high-quality men's discus competition in which three men threw more than 60m, Abdul Buhari's throw of 63.32m was enough for victory. Carl Myerscough was second with 61.63m and should join Buhari at next month's Worlds in South Korea.
Strongly tipped British record holder Lawrence Okoye finished fifth but his coach told BBC Radio 5 Live: "There's a grand prix meet next week at Crystal Palace and that will be his last chance. This was a steep learning curve for him today and there was huge pressure on him."
With European and Commonwealth 110m hurdle champion Andy Turner deciding not to compete, Lawrence Clarke secured the national title in 13.58 seconds.
The 22-year-old failed to meet the 'A' qualification standard but could still be chosen for Daegu if selectors decide his recent performances have been good enough.
In his first high jump competition in two years, Germaine Mason was unable to recapture the form that secured him a 2008 Olympic silver medal.
Mason jumped 2.12m to finish fifth, whilst Tom Parsons won the competition on countback clearing 2.28m - his best of the season.
Martyn Bernard and Robbie Grabarz also jumped 2.28m which does not make the 'A' qualification standard.
Tom Bosworth set a national record in the 5000m walk, winning the event in 19:29.87. Johanna Jackson won the women's race in 21:42.32.
British triple jumper Phillips Idowu pulled out of the event on Saturday.