Bayern Munich boss Carlo Ancelotti says he has been "very surprised" by Javi Martinez's exceptional form so far this season.
Mats Hummels and Jerome Boateng are expected to be Ancelotti's first-choice central defensive pairing this season, but the versatile Martinez, 27, has impressed in the position in the Super Cup triumph over Borussia Dortmund and Friday's 5-0 win against fourth-tier Carl Zeiss Jena in the DFB Pokal.
"To be honest, I've been very surprised by Martinez," Ancelotti told media in eastern Germany. "He was the best player on the pitch against Dortmund and against Jena he reached the same level."
Martinez, who remains Bayern's record signing after his €40 million switch from Athletic Bilbao four years ago, was instrumental in defensive midfield during his debut season as Jupp Heynckes' side won the Treble but he has since suffered with a succession of injuries.
The Spaniard ruptured knee ligaments in the Super Cup against Dortmund two seasons ago, which limited him to a mere 62 minutes of Bundesliga action in the whole season.
Last term, Martinez started less than a third of Bayern's league games, injuring his left knee at the turn of the year, which forced an operation in Barcelona in January. Martinez, who has won 18 caps for Spain, also missed his country's Euro 2016 campaign and Bayern's DFB Pokal final win in May.
With Boateng out through injury and with Holger Badstuber and Medhi Benatia also either out of favour or unfit, Bayern were reduced to playing David Alaba and Joshua Kimmich in central defence for a large chunk of the season.
Bayern took measures to bolster their options with the return of Hummels from Dortmund, and the Germany international is set to start alongside Martinez in central defence in the Bundesliga opener on Friday against Werder Bremen.
Hummels, who had been Dortmund's captain, said he is not daunted by the competition for places once Boateng and Badstuber return from injury.
"It gives you an extra motivation," he told reporters. "This sort of situation can only be positive, as we'll need every player during the course of the season."