The 33-year-old's inclusion has received criticism in some quarters as Valencia has played less than 10 matches in an injury-ravaged season.
"There are players who haven't played much but they are players that you know will be important when they're in the national team," said Gomez.
"I'm not going to throw out Valencia until he tells me he's quitting."
Valencia, 33, is the Ecuador captain and has won 94 caps, scoring 11 goals. Although he spent the last few years of his Old Trafford career as a right back, Gomez said he sees Valencia as a right winger, the position where he made his name and earned a move to United after a string of sparkling displays at minnows Wigan Athletic.
Their best finishes were fourth in 1959 and 1993, both times as hosts.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)