United go into the game on the back of victory over Tottenham.
Giggs told manutd.com: "Arsenal are still a quality team with quality players. On their day they can beat anyone in Europe. They've proved that for years and years now.
"Okay so they've got a few injuries and a couple of players have left but they've still got so much quality there, they've got a great manager and Arsenal are a great club. So you never underestimate teams like Arsenal with their history."