Robson and Watson have played doubles together before
Teenagers Heather Watson and Laura Robson will make their Fed Cup debuts for Britain in next month's Europe/Africa Zone Group 1 matches in Israel.
Last year's US Open junior champion Watson, 18, and 2008 junior Wimbledon winner Robson, 16, join Elena Baltacha and Anne Keothavong in the GB team.
Fed Cup captain Nigel Sears said: "It is the right time for Heather and Laura to try and make it a successful week."
The games will be played in the week beginning 31 January.
Baltacha is the highest ranked of the British women at 55th in the world, while Keothavong is battling her way back towards the top 100 after sustaining a serious knee injury in 2009.
Watson is ranked third in Britain and 176th in the world, while Robson, who is 219th, has been selected ahead of the likes of Katie O'Brien, Naomi Cavaday and Mel South.
Watson said: "I'm absolutely thrilled to have been selected. It's a dream come true as I've grown up watching the competition. I can't wait to head out to Israel with the girls and give it our all."
Britain will be aiming to win a place in the World Group II play-offs in April but, with only two spots available and possible opponents including world number one Caroline Wozniacki of Denmark, competition will be tough.