From Vitai Lampada

There's a breathless hush in the Close to-night—
Ten to make and the match to win—
A bumping pitch and a blinding light,
An hour to play and the last man in.
And it's not for the sake of a ribboned coat,
Or the selfish hope of a season's fame,
But his captain's hand on his shoulder smote
"Play up! play up! and play the game!"

I looked up the meaning of play up in several online dictionaries and the main meaning seems to be "misbehave", the second meaning is "emphasize (something)". Both seem unfit in this context.

What is the meaning of play up in this poem?

From Vitai Lampada:

There's a breathless hush in the Close to-night—
Ten to make and the match to win—
A bumping pitch and a blinding light,
An hour to play and the last man in.
And it's not for the sake of a ribboned coat,
Or the selfish hope of a season's fame,
But his captain's hand on his shoulder smote
"Play up! play up! and play the game!"

I looked up the meaning of play up in several online dictionaries and the main meaning seems to be "misbehave", the second meaning is "emphasize (something)". Both seem unfit in this context.

What is the meaning of play up in this poem?