The former Barcelona goalkeeper completed a loan move to the Belgian club last week and managed to keep a clean sheet on his debut on Saturday with a 2-0 win away to Leuven.
But the former Spain international wasted no time in taking a swipe at his parent club, taking to social media to indicate that he was happy with a first win with Standard, but he also criticised United for making him spend eight months "working alone".
"Happy for first Win for Standard! and for play after 8 months working alone," Valdes' posted on Twitter.
"Thanks to the Standard Supporters."
Happy for first Win for Standard! and for play after 8 months working alone. Thanks to the Standard Supporters ! pic.twitter.com/BzxR8hOZYp— Victor Valdes (@1victorvaldes) January 30, 2016