Cameron Norrie and Katie Boulter beat Stefanos Tsitsipas and Maria Sakkari 4-3, 3-4, 4-3, including 5-4 in a tiebreaker in the deciding mixed doubles set in the Fast4 format, to give Britain a 2-1 win over Greece in the opening match of the eight-team Hopman Cup in Perth.

Norrie also upset the No 15-ranked Tsitsipas 7-6 (6), 6-4 to give Britain the lead before Sakkari beat Boulter 6-0, 4-6, 6-2 in the women’s singles to level the tie.

On Sunday, Norrie and Boulter have an even tougher task against Switzerland’s Roger Federer and Belinda Bencic. On Thursday, they face Serena Williams and Frances Tiafoe.

In Saturday’s other tie, Ashleigh Barty gave Australia a 1-0 lead over France with a 7-5, 6-3 win over Alizé Cornet before Matt Ebden clinched it for the home side with a 3-6, 7-6 (5), 6-2 win over Lucas Pouille.

Pouille and Cornet prevailed in the mixed doubles 4-3, 4-2 to make the final score 2-1 to Australia.

The round-robin format of the Hopman Cup dictates two singles and a mixed-doubles matches in two groups of four. The group winners face off in next Saturday’s final.

The most keenly awaited match of the eight-team tournament is scheduled for Tuesday when Federer and Bencic play Williams and Tiafoe. It means Federer and Williams will play against each other in the mixed doubles portion of that match.