Britain's top two mixed doubles pairs will continue their battle for Olympic places at the All England Championships in Birmingham from Tuesday.
With only one guaranteed GB pair in London, Chris Adcock and Imogen Bankier currently lead Nathan Robertson and Jenny Wallwork in the world rankings.
Birmingham is the last premier event before the Olympic qualifying race comes to a close at the end of April.
The world rankings on 3 May will be used to decide who makes it to London.
Britain looks likely to have one player or team in each of the two singles and three doubles events at this summer's Games.
Adcock and Bankier, who won a surprise silver medal at last year's World Championships, are ranked 14th in the world - four places higher than Robertson and Wallwork, who have struggled for consistency in the last year.
"We get to train against each other and we're bringing each other on all the time," said Bankier. "It's a testament to how good they are that we've improved and likewise the rivalry keeps us both on our toes."
Robertson and Wallwork gave their hopes a boost by beating Adcock and Bankier in Malaysia in January - the first competitive meeting between the British pairs - and followed it up by winning the Swedish International title.
"We're in a straight shoot-out with the other GB pair for the spot," said Robertson, a silver medallist with Gail Emms at Athens 2004 and preparing for his last All England Championships. "It's really tight."
With ranking points and Olympic qualification on the line, the All England Championships carry even greater significance than usual this year.
British men's number one Rajiv Ouseph faces a tough task against fourth seed Peter Gade in round one, with Ouseph never having taken a game off the Dane in seven meetings.
English champions Chris Adcock and Andrew Ellis begin their men's doubles campaign against Indonesia's Alvent Yulianto Chandra and Hendra Aprida Gunawan, while Mariana Agathangelou and Heather Olver play sixth seeds Shizuka Matsuo and Mami Naito in the women's doubles.
On the opening day of action on Tuesday, Elizabeth Cann failed in her attempt to qualify for the main draw as an energy-sapping victory earlier in the day caught up with her in the evening.
The Jersey player, ranked 55 in the world, came through a tough three-game contest against Italy's Agnese Allegrini 17-21 21-14 21-17 but then found the turnaround before facing Maria Febe Kusumastuti of Indonesia too quick, losing 21-11 21-10 in 30 minutes.
Cann progressed one round further than Scotland's world number 39 Susan Egelstaff - her chief rival for a women's singles spot at the Olympics - who lost 21-17 21-8 to the same opponent.
Scotland's Robert Blair and Jillie Cooper won through to the main draw of the mixed doubles with a 21-17 19-21 21-8 win over Yu Lang Lin and Pei Chen Hsieh of Taipei in their second-round qualifier.
But there was disappointment for Marcus Ellis and Heather Olver as they went down 16-21 23-21 22-20 to Japan's Noriyasu Hirata and Miyuki Maeda in the second qualifying round.