Rinaldi said she expects Williams, who was named in the U.S. squad that will compete on an indoor hard court in Asheville, North Carolina, to make a smooth transition in her return to competitive tennis.
"Serena's just coming back. She played an exhibition in (December) and it's incredible," Rinaldi told a news conference at the U.S. Cellular Center in Asheville.
"It's a quick turnaround after having her first child. She's very professional and she has a lot of pride for playing for her country. She'll be ready to go."
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Williams, 36, has played once since winning an Open-era record 23rd grand slam singles title in Melbourne last year, losing to Roland Garros champion Jelena Ostapenko in an exhibition match in Abu Dhabi last December.
For Williams, this weekend will mark the first time she has competed in a Fed Cup tie since April 2015. She owns a 13-0 singles record and 3-1 doubles record in Fed Cup competition.
She heads a team made up of older sister Venus, world number 17 CoCo Vandeweghe and world number 62 Lauren Davis. The United States beat Belarus last year for a record-extending 18th Fed Cup title, their first in 17 years.
The Netherlands squad is comprised of world number 108 Richel Hogenkamp, Arantxa Rus (124), Lesley Kerkhove (165) and Demi Schuurs, who is ranked 32nd in doubles.
Netherlands captain Paul Haarhuis said his squad would have to pull off what he felt might be "the biggest upset in U.S. tennis history" to win.
"If you look at Serena, how often does she lose to someone that's not ranked in the Top 10 or Top 20 or outside the Top 100?" said Haarhuis. "The odds are not good, but we do believe that it's possible.
"We're the underdog by far, that won't change if they bring in five new players, we're still the underdog, but we still have to believe that it can be possible."
Play begins on Saturday with two singles matches and will continue on Sunday with two reverse singles matches and the doubles match.
The winner advances to the April 21-22 semi-finals.
(Reporting by Frank Pingue in Toronto; Editing by Toby Davis)
