Yuki Bhambri and Matthew Ebden fought hard before losing 4-6, 6-7 (2) against the top-seeded Australian-Kiwi combination of
Unseeded Yuki Bhambri and Matthew Ebden came from a set down to stun second-seeded American pair of Austin Krajicek and Nicholas Monroe 5-7 6-4 10-8 in the doubles semifinals.
The world number 11 crushed Australian wild card Matthew Ebden 6-2, 6-4, 6-3.
The 100th-ranked Johnson will be playing in the singles at the grass-court Grand Slam tournament for the first time since becoming a full-time professional last summer. He won the ATP Challenger title at Nottingham last week to earn his wild card, which was announced on Tuesday.
Also receiving wild cards were Australia's Matthew Ebden, who won the mixed doubles title at the Australian Open in January with Jarmila Gajdosova, and Germany's Andrea Petkovic.
The 20-year-old downed Istomin 4-6, 6-2, 6-2, 6-3 in the fourth rubber to clinch Australia a place in September's World Group playoffs.
Bernard Tomic was badly beaten in the first round for a third straight tournament, with the Australian number one shunted out of the Swiss Indoors 6-0, 6-2 on Tuesday by Mikhail Youzhny.
Australia progressed to the Davis Cup World Group playoffs for the third straight year when Marinko Matosevic and Chris Guccione recorded a 4-6, 6-1, 6-4, 6-2 doubles win over Jeong Suk-young and Seol Jae-min of South Korea on Saturday.
Bernard Tomic and Matthew Ebden gave Australia a 2-0 lead over South Korea with wins in the opening singles of the Davis Cup Asia Oceania Group 1 second round tie in Brisbane on Friday.
Bernard Tomic of Australia will play South Korea's Cho Min-hyeok in the opening singles match Friday in an Asia-Oceania second-round Davis Cup qualifier.
Denis Istomin saved all seven break points he faced on serve en route to a 6-2, 6-3 win over Aussie Matthew Ebden in the first round of the Delray Beach Tennis Championships on Monday.
Red hot Andy Murray cruised into the semi-finals of the Shanghai Masters on Friday, notching his 13th straight victory.
Just three days after winning the French Open for a sixth time, Rafael Nadal began his preparations for Wimbledon with a 6-4, 6-4 win over Australian qualifier Matthew Ebden in his opening match at Queen's Club on Wednesday.
Australian qualifier Matthew Ebden earned a shot at world number one Rafael Nadal thanks to his 7-5, 6-3 win over India's Somdev Devvarman at Queen's, while four-time champion Andy Roddick defeated Feliciano Lopez 7-6 (7/2), 6-7 (5/7), 6-4 on Tuesday.