Two-time Formula One world champion Fernando Alonso will headline the Rolex 24 at Daytona for the United Autosports sportscar team beginning Saturday.

The Spaniard missed the Monaco Grand Prix to compete in the Indy 500 in May and returns to the United States to enter his first endurance event.

Alonso, who signed a new contract to remain with McLaren for the 2018 F1 season, will join Phil Hanson and Lando Norris in racing the Ligier JS P217 in the prestigious event, competing with teams from across the globe for a grueling 24 hours on Daytona International Speedway's 3.56-mile combined road course.

For those new to racing or the event's unique rules, here's a rundown on what you need to know about the Rolex 24.

When does the Rolex 24 begin?

The 56th running of the Rolex 24 is set to start at 2:40 p.m. ET Saturday.

What types of cars race in the Rolex 24?

There are 50 cars entered across three classes – Prototype (P), GT Le Mans (GTLM) and GT Daytona (GTD).

The race is sanctioned by the International Motor Sports Association, or IMSA, and is the season's first race for the WeatherTech SportsCar Championship. Unlike NASCAR and IndyCar, a multitude of manufactures will be featured in the race including Lexus, McLaren, Porsche, Ferrari, BMW, Cadillac, Nissan, Acura, Mazda, and more.

What are the rules of the Rolex 24?

Teams of up to five drivers compete in a 24-hour relay race. No driver can be in the car for more than four hours of a six-hour period.
At the race's end, the team driving the most miles in each car class wins.

All cars featuring pro drivers will have a red tag affixed. Models with pro-am drivers will have green number panels. All car types will be on the track at once, making for a challenge for the faster teams weaving through traffic.

Drivers must adhere to pit-road speed like any other race. But they aren't the only ones switching off every two to three hours. Teams will switch crew chiefs and other personnel throughout the race to stay fresh. Crews are allowed to nap between shifts but must stay within reach of their team should a problem arise.

Who are the drivers to watch in the Rolex 24?

Four Indianapolis 500 winners will join Alonso as the drivers to watch in this year's edition: Scott Dixon, Helio Castroneves, Juan Pablo Montoya, and Ryan Hunter-Reay.

Four drivers – Dixon, Simon Pagenaud, Hunter-Reay and Scott Sharp – have also claimed IndyCar season championships. Sebastien Bourdais, who currently drives IndyCar, is a four-time champion of the now-defunct Champ Car Series.

Longtime road course racing standout AJ Allmendinger and five-time Rolex 24 winner Scott Pruett (retiring after race) are also ones to watch. Justin Marks, who won a 2016 Xfinity race at Mid-Ohio Sports Car Course, is also competing.

Full lineup of teams and drivers.

How can I watch the Rolex 24?

Coverage begins Saturday at 2 p.m. ET on Fox, with coverage moving to Fox Sports 2 at 5 p.m. Here is the full broadcast schedule:

Saturday, January 27
2 p.m.: Fox
5 p.m.: FS2
10 p.m.: Fox Sports Go
11 p.m.: FS1

Sunday, January 28
1 a.m.: Fox Sports Go
8 a.m.: FS1
10:30 a.m.: Fox Sports Go
1 p.m. to finish: FS1