Chloe Tutton and Molly Renshaw sailed into the 200m breaststroke semis on the fifth day of swimming at the Olympic Aquatics Centre.
Both 20-year olds are making their Olympic debuts in Rio, but clocked times to match the best in the world as they qualified in fourth and fifth respectively.
Having reached the 100m breast semis earlier in the week, Cardiff-based Tutton was the quicker of the two, finishing third in her heat in 2:23.34.
Renshaw was just 0.03 seconds back after her 2:23.37 effort to touch second in her heat, coming just 0.19 seconds shy of her English record set to finish fourth at this year’s European Championships in London.
“I think that went really well,” said Tutton. “It was nice and smooth and chilled this morning so I’m happy to have qualified for the semis tonight.
“The goal was just to qualify. I just needed a place in that semi final but I was really nervous beforehand. So it was nice to be so calm and smooth.
“I got my head together on the block and realized I was actually racing. I managed to get into a rhythm.”
Renshaw added: “I knew it would take a strong heat swim this morning to make it through so I was trying to focus on the process rather than the outcome and it worked for me.
“I’ll try and do the same again tonight and obviously move the time on a little bit. I will just stick to my race and keep it long and strong.”
Dan Wallace and Ieuan Lloyd also booked semi-final places for tonight, finishing 11th and 15th overall from the 200m individual medley heats.
Wallace was part of last night’s silver medal-winning 4x200m freestyle relay quartet, and clocked a 1:59.44 effort to progress.
Lloyd was just 0.3 seconds back, progressing on 1:59.74 after touching sixth in his heat.
The women’s 4x200m freestyle relay team narrowly missed out on completing a perfect set of qualifiers in the pool as they finished ninth from the heats.
Siobhan-Marie O’Connor, Georgia Coates, Hannah Miley and Camilla Hattersley came home in 7:54.17 with Sweden claiming the eighth qualification spot on 7:53.43.