According to Jugones (h/t Sport), Solari will be fired around 6 p.m. local time on Monday, and following successful negotiations with Madrid president Florentino Perez, Zidane—who left the club last summer—will take his place on Tuesday.
However, El Pais (h/t Calciomercato.com) reported Zidane has also been in touch with former club Juventus and "has a formal offer to lead Juventus until 2022."
Zidane managed Real for two-and-a-half years, and in that time he won three consecutive UEFA Champions League titles and La Liga.
His successor at the Santiago Bernabeu, Julen Lopetegui, lasted just 14 matches before he was fired having won fewer than half of them.
Solari oversaw an improvement, but in the space of a week, he saw Real crash out of the Champions League against Ajax after Barcelona had pulled the curtain on their hopes in La Liga and the Copa del Rey, all at the Bernabeu.
ESPN's Dan Thomas nevertheless felt he should remain in charge until the end of the season:
With Zidane seemingly set to return, it appears Real have no need for a lengthy search for Solari's successor.
SB Nation's Lucas Navarrete believes Zidane will be given the tools he needs to reshape the squad as he sees fit:
AS' Robbie Dunne feels Real could have avoided such a disappointing season by giving him what he wanted last summer:
It will be a difficult job, more so than when the Frenchman took charge the first time.
Los Blancos are now without Cristiano Ronaldo, Sergio Ramos is almost 33 and LukaModric nearly 34.
Several other core players, such as Gareth Bale, Toni Kroos and Marcelo, aren't quite as old at 29 or 30, but they've each had poor seasons—the former and the latter in particular.
La Liga writer Andrew Gaffney believes returning to Real is a gamble on Zidane's part:
Juventus might not be easy, either, given they're in the process of transitioning away from veteran defenders Andrea Barzagli (37) and Giorgio Chiellini (34), but they have less competition domestically than Real, and unlike the Spanish giants, they're not a club in crisis.
For all the success he delivered first time around, a return to Real will be a huge test of Zidane's managerial capabilities.