NFL teams, including the Seattle Seahawks, use Microsoft Surface tablets on the sidelines to quickly review past plays during a live game. (GeekWire Photo / Kevin Lisota)

Microsoft and the NFL are expanding their alliance to bring more technology to one of the world’s most popular professional sports leagues.

NFL players and coaches will continue using Microsoft Surface tablets on the sidelines during games as part of the new multi-year expansion deal announced Tuesday. The partnership now includes Microsoft’s Teams collaboration tool, which will be used by both teams and NFL staff.

It’s a notable deal for Microsoft, which has already deployed more than 2,000 Surface devices across the league. Players in others pro sports leagues such as MLB use Apple iPads during games.

Terms of the new deal were not disclosed. The alliance dates back to 2013, when Microsoft inked a reported $400 million, 5-year deal with the NFL.

The custom-built Surface devices and their signature blue cases are well-known in the NFL world, partly for the odd interactions players and coaches have with the tablets. But after some early hiccups and criticism, they are now a mainstay on the sidelines, a key strategic tool that replaces paper printouts previously used to review past plays. Officials use the tablets during in-game replay reviews.

The partnership is also an advertising vehicle for Microsoft. The Surface is the “official laptop of the NFL,” and the “official sideline technology provider.” The tablet was featured in Microsoft’s Super Bowl ad in January.

NFL viewership increased this past season by 5 percent to about 16.5 million viewers per game on average.

A bin of Surface tablets at a game in Seattle. (GeekWire Photo / Kevin Lisota)

Teams and NFL staff will also now take advantage of Teams, Microsoft’s collaboration software.

“Microsoft Surface has quickly become an authentic tool to the game of football and is vital during all NFL games for coaches, players, and NFL officials,” Renie Anderson, chief revenue officer and executive vice president of NFL partnerships, said in a statement. “And now by working together to integrate Microsoft Teams across the League, together we aim to improve on communications and collaboration in a modern way.”

The Miami Dolphins already used Teams to organize Super Bowl planning this year; the Super Bowl champion Kansas City Chiefs deploy it to coordinate between accounting teams and scouts on the road; and the New York Jets use the tool across the front office, including the NFL Draft process.

Adding Teams to the NFL alliance could give a major boost to the collaboration tool as Microsoft battles Slack and others. Microsoft said last year that Teams has more than 20 million daily users.

Microsoft also has 170 Windows servers across 35 stadiums around the world that help more than 333 games per season go off without a hitch.

Seattle Seahawks wide receiver Tyler Lockett reviews a play on a Surface tablet during a game this past October. (GeekWire Photo / Kevin Lisota)

The NFL considered adding real-time video to the tablets for view during games but has yet to allow the functionality.

Still images with a bird’s-eye view are captured by a camera in the coaches booth and sent to the tablets in real-time thanks to a private WiFi network built specifically for the Surface devices. Teams can also take the tablets with them into the locker room during halftime.

Microsoft improved the functionality of the device over the past several seasons and streamlined the process of how players and coaches view game footage. The software lets teams create individual profiles for coaches that provide easy access to specific types of past plays. For example, the “defense” profile will surface all defense-related plays, while a “punt return” profile will do the same for punt-related plays.

Each image can be tagged and annotated by coaches. Those edits show up immediately — for example, if a coach in the booth makes a note on one tablet, that shows up in near real-time on a separate tablet being used by a player on the sideline.

The tablets themselves are custom-built to withstand extreme temperatures and force. They are waterproof and decrease reflectivity from the sun.

Microsoft’s Surface division reported an all-time high in revenue in the most recent quarter. However, the $1.98 billion in revenue actually fell short of internal expectations, following a big product reveal event a few months prior.

The NFL has embraced multiple technology providers to up its level of innovation. Microsoft’s rival Amazon has a streaming deal for Thursday Night Football games, while its cloud unit Amazon Web Services powers the NFL’s Next Gen Stats program and has a separate deal with the Seattle Seahawks.

Google, meanwhile, announced is own expanded partnership with MLB on Tuesday.