Daniel Rowden powered past Jake Wightman to take the British 800m title in a thrilling finish in Manchester.
Rowden, 22, had surgery in April 2019 but looked back to his best as he surged past 1500m Commonwealth bronze medallist Wightman on the home straight to win in 1:45.94.
Yusuf Bizimana finished third with Elliot Giles, Kyle Langford and Guy Learmonth absent after competing in France on Thursday.
"It's very special," Rowden said.
"It's been such a weird year. It was a tough road back. I had surgery in April 2019. It sorted me out but it took me a while to get back going again.
"To be out here and take the title is incredible."
Teenager Max Burgin, who ran the eighth fastest 800m time in the world this year, pulled out injured earlier this week.
Lake and Bradshaw add another title to their collection
In the field, Morgan Lake claimed her fifth successive national high jump title on countback. The 23-year-old Commonwealth Games silver medallist cleared 1.80m - well below her personal best of 1.97m - and Jodie Smith finished second on the same height.
European bronze medallist Holly Bradshaw won her eighth national pole vault title, stopping the competition after her title-winning jump of 4.35m.
"I've had a really rough 24 hours," she said. "My granddad passed away yesterday. He was one of my biggest fans.
"I felt it was appropriate to come and try my best. I'm glad I came and became British champion. He would be really happy."
Knight claims title before new school year begins
In the absence of Meghan Beesley, primary school teacher Jeesie Knight powered to a dominant win in the 400m hurdles, finishing more than a second clear of Lina Nielsen in 55.8.
"I know a couple of girls are missing but I feel like I've been running times this year so I'm really happy," Knight said.
"I missed out on the World Championships last year and this year I've run the Olympic qualifying time so fingers crossed it goes ahead and I'll be there.
"I haven't met my new class at school yet. I can't wait to meet them all."
Naomi Ogbeta - who had coronavirus in March - won the triple jump with 13.44m while Laviai Nielsen successfully defended her 400m title, winning in commanding style with a new seasons best of 51.72.
Mills makes dad proud with 1500m win
George Mills, son of former England and Leeds full-back Danny, held off Neil Gourley and Josh Lay to win the men's 1500m title, while Commonwealth silver medallist Laura Weightman won more comfortably to earn her fifth national title over the distance.
With world champion Dina Asher-Smith not competing and pre-race favourite Kristal Awuah disqualified for a false start in the heats, Hannah Williams ran 200m in 23.83 to claim the title won by her older sister Jodie last year.
Andrew Morgan-Harrison overcame a hamstring injury to win the men's event in 20.69 with the tailwind over the legal limit.
Alex Knibbs, who usually competes in 400m hurdles, ran down almost the whole field on the home straight to win the men's 400m in a personal-best 46.65 while Guernsey's Alastair Chalmers eased to victory in the men's 400m hurdles.
Nathan Douglas' final-round jump of 15.80m helped him see off Sam Trigg-Petrovic's challenge for the men's triple jump crown.
A gutsy performance from Aimee Pratt, running out on her own throughout the race, won her the 3,000m steeplechase title in 9:30.73 - the best time in the world this year and a personal best with Phil Norman winning the men's event.
Paralympic champion Brent Lakatos and Zac Shaw were both winners as para-athletics events were included for the first time.
It was a comfortable victory for Marc Scott in the men's 5,000m, while 18-year-old Keely Hodgkinson won the women's 800m title.
There were also wins for Gemma Bridge and Callum Wilkinson (5,000m walk), Freya Jones (javelin), Scott Lincoln (shot put), Craig Murch (hammer) and Nick Percy (discus).