Pakistan, Sept. 3 -- French showman Gael Monfils celebrated his 40th birthday with a 2-6 6-1 6-2 6-0 win over Adolfo Daniel Vallejo to reach the second round of the US Open on Tuesday, keeping his farewell Grand Slam campaign alive. A day after fellow veteran Stan Wawrinka played the final Grand Slam match of his career, Monfils showed he was not ready to follow him out the door yet, drawing huge applause from fans on Louis Armstrong Stadium as he fought back from a slow start. Monfils also became the oldest player to win a main-draw singles match at Flushing Meadows since Jimmy Connors defeated Jaime Oncins on his 40th birthday in 1992. There was no cake on court, but Monfils received a rendition of "Happy Birthday" midway through his sp...