be on the offensive

To be in a mode of attack or aggressive action as a means of gaining an advantage; to be on the attack. If you aren't on the offensive as soon as the debate starts, your opponent is going to walk all over you! After spending weeks dodging scandal, his campaign is on the offensive again, accusing his opponent of misstating the facts. They're a team full of slick scorers, so you know they'll be on the offensive from the moment the puck drops.

be on the ofˈfensive

be attacking somebody/something rather than waiting for them to attack you: The Scots were on the offensive for most of the game. ♢ The government is very much on the offensive in the fight against drugs. OPPOSITE: on/onto the defensive