Jacob Richards was already a world champion. Now the Welsh swimmer was trying to beat his best friends.

At the Commonwealth Games in Birmingham, four British swimmers who won gold together as part of a world champion relay team found themselves on opposite sides. Richards represented Wales. His teammate stood for Northern Ireland. Another swam for Scotland, and one for England.

Richards had already collected three medals at these Games, though he was still hunting for his first gold. On Wednesday, he and Jack McMillan from Northern Ireland swam in the same heat as Scotsman Evan Jones and Englishman Tom Dean — all four of them former world champions together.

"We're all good friends and that camaraderie helps us as teammates, but also as rivals to push each other," McMillan said. "We play our roles when it comes to the relay, but swimming is an individual sport too."

The four swimmers train together most of the year as part of Team GB, the national team that represents Great Britain at Olympic-level competitions. The Commonwealth Games are different. Every four years, British athletes compete for their home nations instead — England, Scotland, Wales, or Northern Ireland.

"It's actually really cool because it's very rare we represent our home nations," said English swimmer Daniel Guy. "It's really weird being part of different countries when you're together most of the time as Team GB."

Australia has dominated the swimming events at these Games, but Richards' teammate Josh Scott, who won gold in Glasgow at the previous Commonwealth Games in 2014, said all four friends have their eyes on the top spot.

"We go head to head so much at British Championships year in and year out, in season meets, that it's always good fun racing those boys," Scott said. "Ultimately we all want to see each other swim well."

Richards echoed that spirit. "We just want to see ourselves swim that tiny bit better," he said.

So who will have the last laugh? The swimmers kept their sense of humour about the unusual situation. But on race day, friendship takes a back seat to the lane lines.