This is another 30 second timer level that is dependent on your speed and ability to collect the various clock pickups littered across the course. Rush forward at the beginning and collect Green Star #1 from atop the Goomba Tower, then quickly move past the clear pipes (probably easier to go on top of them) that have Fire Bros on the other side. When you get to the Fire Bars, Ground Pound the second ?-Block to get boosted into the air for a clock pickup. Defeat the Fire Bro atop the Goomba Tower just past there to spawn a Warp Box and go to the second area.
As soon as you appear in the second area, quickly get on top of the nearest Thwomp, then jump up to the wall. Dash to the left and at the end, collect Green Star #2. Rush to the right now, then just choose a pipe and go through it. You should see a light spot on the ground just past the Fire Bro, so perform a Ground Pound on it to get Green Star #3. Collect the clocks on top of the POW Blocks, then enter the pipe to head to the next section. Swiftly eliminate the Fire Bro here, then take the Warp Box to the Goal Pole area, where you can cap the flagpole by jumping off of the Fire Bro.