Carry the ball
Definition 1 of 2
Pro Tip 1/3Taking Initiative
Used when someone proactively takes charge without being prompted by others. 
When the community event was in disarray, Maria decided to carry the ball and organized the volunteers.
Pro Tip 2/3Not Literally
It's a metaphor and doesn't involve physically carrying anything. 
After the CEO retired, Jenna had to carry the ball and lead the company.
Pro Tip 3/3Leadership Quality
Often implies leadership qualities or readiness to step up. 
With the captain ill, the young lieutenant had to carry the ball.