Question: When was the first tennis major comprising the Grand Slam before the US Open first held?

Related documents: [0]  [DOC] The United States Open Tennis Championships is a hard court tennis tournament. The tournament is the modern version of one of the oldest tennis championships in the world, the U.S. National Championship, for which men's singles was first contested in 1881. Since 1987, the US Open has been chronologically the fourth and final tennis major comprising the Grand Slam each year; the other three, in chronological order, are the Australian Open, the French Open and Wimbledon. [END] 
[1]  [DOC] The Australian Open is a major tennis tournament held annually over the last fortnight of January in Melbourne, Australia. First held in 1905, the tournament is chronologically the first of the four Grand Slam tennis events of the year – the other three being the French Open, Wimbledon and the US Open. It features men's and women's singles; men's, women's and mixed doubles and junior's championships; as well as wheelchair, legends and exhibition events. Prior to 1988 the tournament had been played on grass courts, but since then two types of hardcourt surfaces have been used at Melbourne Park – green coloured Rebound Ace up to 2007 and, afterwards, blue Plexicushion. [END]  
Answer: 1905
1905