5 key battles to watch in the Round of 16

Sixteen teams remain in contention for the the 2016-17 Champions League crown, and over the next two weeks, those clubs will play the first leg of their respective ties, with plenty of star power on offer across the board.

Here are five key battles to watch in the Round of 16:

Reunited: Umtiti vs. Cavani

In this clash of giants, Paris Saint-Germain's Edinson Cavani takes on a familiar foe in former Lyon defender Samuel Umtiti, who is likely to start alongside Gerard Pique for Barcelona in the absence of Javier Mascherano. You could call it a reunion, but the two meet under very new circumstances.

Cavani is now free of the shadow cast by Zlatan Ibrahimovic and has notched 33 goals in all competitions as PSG's new target-man. He is no longer limited to a wing role and, as such, center-back Umtiti will need to deal with the Uruguayan directly, rather than rely on his full-backs.

Exposed: Insigne vs. Danilo

Napoli hasn't missed a beat since Gonzalo Higuain left, with Dries Mertens and Marek Hamsik performing wonderfully and Arkadiusz Milik helping fill the void before his untimely injury. A meeting with goal-heavy Real Madrid might be a nightmare for both goalkeepers.

But the real battle isn't central, due in part to the abundance of quality from both sides in their cores; it's out wide, where Lorenzo Insigne will be tasked with besting Madrid right-back Danilo in the absence of Dani Carvajal. Danilo has looked suspect at times, a flaw Napoli will look to exploit.

Heavyweights: Boateng vs. Sanchez

Bayern Munich and Arsenal meet in a repeat of last year's Group F encounters, and while the German outfit certainly got the better of the Gunners with a 5-1 win at the Allianz Arena, things have changed considerably for Arsene Wenger's side. Most notably, Alexis Sanchez has been moved to centre-forward.

Since making the switch, the Chile international has enjoyed a prosperous scoring streak in the Premier League, notching 17 goals this season. He'll be a handful for Jerome Boateng, who handled Olivier Giroud well enough last year, but could face a different, if not more difficult test this time around.

Trapped: Monaco wingers vs. City's full-backs

Pep Guardiola is perhaps a little unsure of how to line up his back-four for Manchester City's upcoming match against AS Monaco. Against Swansea, he opted to use defensive midfielder Fernandinho as a right full-back, and against Bournemouth, he went one step further, placing the Brazilian at left full-back.

Whichever side Fernandinho ends up playing, he'll have to deal with a tricky and pacey winger; the likes of Thomas Lemar, Bernardo Silva, and Kylian Mbappe have all been outstanding this season. With Falcao and Valere Germain prowling the box, getting exposed out wide could prove costly for City. For all his positives, Fernandinho is not a natural in this position.

Worthy: Soares vs. Bonucci

City may be enjoying the advent of newcomer Gabriel Jesus but FC Porto has its own fresh Brazilian signing to celebrate in Francisco Soares, known as Tiquinho. The 26-year-old joined the club in the new year and has already made his presence felt, scoring four times in three appearances.

As expected, the hype surrounding him has grown exponentially, but Soares will have his first chance to really turn heads with a solid showing against a competent Juventus backline. The Italian giant boasts one of the finest defensive systems in the world, and while Andrea Barzagli and Giorgio Chiellini are dealing with injuries, how Soares handles Leonardo Bonucci in particular will be interesting to see.