BOSTON -- Capitalizing on a break in the rain, singer Neil Diamond and the Boston Pops orchestra scrambled onto the Hatch Shell stage for a quick rehearsal on Friday morning as organizers prepared for the city’s annual Independence Day celebration.

Diamond and The Boston Pops Esplanade Orchestra will perform a concert on Friday night before taking the stage Saturday at Boston’s 4th of July fireworks show and concert.

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Preparations for the concert were stalled by persistent rain that threatened to wash out celebrations in many Massachusetts towns. Organizers said they expect to be ready on schedule for the festivities this weekend, despite the delays.

"We're pretty much on track,” said event producer Rich MacDonald. “I mean, people put in a long day yesterday and they pretty much got caught up and today now is our rehearsal."

Puddles and patches of mud lingered on the grass lawn in front of the Hatch Shell, and MacDonald warned that concert-goers may want to bring a tarp or a tent to wait out the beginning of the show. Tents are allowed on the lawn until 6 p.m. before the concert, MacDonald said.

Television personality Craig Ferguson will host this year’s event, which is expected to draw more than 500,000 spectators. The concert will begin at 8:30 p.m., leading into the fireworks show between 10:30 and 11 p.m.

“I’ve said for years if we can just get Neil Diamond to come sing ‘Coming To America,’ we can just pack it up and go home -- it’ll be a great show,” said Boston Pops director Keith Lockhart.

Organizers stressed that tarps should not be larger than 8 feet by 10 feet. Alcohol, glass containers and sharp objects are also banned from the oval lawn in front of the Hatch Shell.