Sanchez is Arsenal's Suarez - Mascherano
Alexis Sanchez arrived at Barcelona the summer after they had won Pep Guardiola's second Champions League at Wembley in 2011. And he left the season before they were triumphant in Berlin in 2015.
One league and one cup in his three-year spell can seem like a relative failure. Don't try telling Mascherano that.
"He delivered in the time he was here," he says. "He was very involved. Maybe he just needed the challenge of having a greater part to play in another team.
"Now he has a huge role to play for Arsenal. He is crucial to what they do. His aggression and attitude is infectious."
He sounds like the player who replaced him at Barça? "Yes. Totally, there is a touch of Luis Suarez. He is a fighter. He never gives up a single ball for lost. He is always going to give everything. And that is fundamental for any team."
Barça are not taking Arsenal lightly. Mesut Özil is another who will be well known to them on Tuesday. He made 17 assists in 2011-12 when Real beat Barça to the title.
"Özil is key. Everything revolves around him," says Mascherano. "They have a very good midfield and they are always competitive. In the last two years they have raised their level, especially against the big sides.
"They are not going to change because they're facing us."
In 2011 when a late goal from Nicklas Bendtner would have put Arsenal through it was you know who, appearing from nowhere, robbing the Dane that saved Barça.
"That tackle marked a before and after for me, in terms of my adaptation," he says. "I found it hard to adjust. But from that game on I started to play as a centre-back. If Bendtner had controlled the ball he would have gotten away. But it happened the way it happened and we won the Champions League."
Both Özil and Sanchez are expected to be rested by Arsenal today when - for the third consecutive year - they face Hull City in the FA Cup.
After his winner against Leicester last weekend, Danny Welbeck may get a chance to impress from the start.
Arsenal v Hull City, live, BT Sport 2, 12.45