How Mendy and Alaba compliment each other to enhance Real Madrid’s left-flank when paired together

These observations — where I look at Real Madrid’s history, its players on loan, Castilla, tactical tidbits, and other relevant thoughts — are now a regular thing. All previous editions can be found here.

As we approach — several hours away now — Real Madrid’s first Champions League of the season tonight against Celtic, I thought I’d discuss one interesting tactical wrinkle — a continuation from last season at Real Madrid’s left-back slot.

I’m not sure who Carlo Ancelotti will start tonight at the back vs Celtic, though if I had to wager, Antonio Rudiger gets a nod in the XI. Will tonight’s line-up be a primer — a sneak peak — of the Gala XI which Ancelotti will roll out in the upcoming Madrid Derby, Clasico, and Champions League knockout rounds? Rudiger, David Alaba, Ferland Mendy, and Eder Militao are all starting-calibre defenders. How Ancelotti sees his best back-four is still relatively unknown.

But I do want to discuss two players in particular: Mendy and Alaba. Mendy locks down superstar wingers in impressive fashion. Alaba provides more going forward, and can actually put in accurate crosses will combining better with Vinicius.

But when debating who should start at left-back, we often forget one important factor: Both can start and play left-back in the same game. Alaba is better at center-back; Mendy is better at left-back. You’ve already seen elite ball progression from the former at the LCB position this season. You’ve also seen Mendy barricade the left flank — as well as Alaba providing important runs in the final third on that same side.

All of those things happened with both of them on the field together against Real Betis at the Bernabeu on Saturday night.

This wrinkle, where Alaba and Mendy seamlessly switch roles on the fly, surfaced again from last season, and quite simply, it works. In real time, the switch happens quite subtle, like this:

After battling a press, Alaba’s off-ball movement finds himself driving forward. Mendy recognizes immediately and drops back. That’s the best solution if you want Mendy’s defense and Alaba’s ball-progression. Perhaps in other partnerships the switch is more challenging, but the understanding between these two is cerebral, and well-oiled enough to take advantage of regularly.

Mendy didn’t enter the final third much vs Real Betis. Alaba took up real estate there more. Against Almeria, the French left-back had plenty of touches high up the pitch, but many were clumsy and out-of-sync with Vinicius. Ancelotti can optimize the strength of both him and Alaba this way, deploying them together as a two-headed two-way tank.

Alaba, in turn, is smart enough to cover a lot of ground. Against Betis, he played everything from left-center-back to left-back, and even inverted left-back. What’s more, is that Mendy mirrors the understanding and does the same. There is a fluidity to them. Watch how Mendy moves to create passing avenues:

Mendy’s press-resistancy is underrated. He’s labelled as being bad on the ball, but that’s contextual to him taking players on in the final third. Under pressure, he’s been reliable dribbling out of trouble, and his passing accuracy, four games into the league season, is at 94% (the highest in the entire league).

Alaba’s been vital too, and already has three goal-creating actions in La Liga (fifth most).

There is no definitive answer yet on what the best combination of players form Real Madrid’s most potent backline (though I do believe it will involve Rudiger), but it’s important to note that the concerns over Mendy’s lack of offensive puissance can be mitigated by pairing him with Alaba.