One of Jupp Heynckes' first moves after returning to Bayern Munich last month was to restore Javi Martinez to the defensive midfield role in which he excelled during the veteran coach's previous spell, and so far the results have been spectacular.

No pain, as they say, means no gain.

Watch: Javi Martinez: Bayern's midfield rock!

Bayern's UEFA Champions League win over Celtic in October was a perfect illustration of just what Javi Martinez brings to the side. Having had their early lead pegged back with 16 minutes of normal time remaining, the Spaniard stepped forward, in a position he is not usually seen, to win the game.

When David Alaba whipped a superb ball across to the edge of the six-yard box minutes after Celtic's equaliser, the 29-year-old showed great bravery to leap above Hoops defender Nir Bitton and nod in the winning goal, his very first in the Champions League. The clash with the Israeli opened up a nasty wound on the Bayern man's head and he required several minutes of treatment to patch it up. Martinez later posted a picture of his blood-stained face on Instagram, acknowledging the date – October 31 - with the wry message 'Happy Halloween!!'.

"I tried to hit the ball with my head, my heart, with everything I had - and thank God, it went in!" said a breathless Martinez after the game. "It hurt, but I would happily take a blow like that every game if it meant I scored a goal. It's only blood."

"The coach wasn't entirely happy that I was so far forward at that moment in the game," he continued with a smile. "But I know this position like the back of my hand, I've been there for a long time, and I felt I could add an element of danger if I went further up."

Martinez's knowledge of the position in question - defensive midfield - is one of the factors underlying Bayern's dramatic upswing in fortunes since Heynckes returned to Säbener Strasse for a fourth stint at the helm. After being deployed as a central defender by previous coaches Pep Guardiola and Carlo Ancelotti, the former Spain international has returned to his favoured role - the very one that Heynckes had in mind when he signed him for a then club record fee from Athletic Bilbao in August 2012.

"Javi has played in central defence before, but I have a rather different opinion," the 72-year-old confided after the Celtic win. "Since he's been playing in midfield we've improved our stability and the quality of our defensive work. He's also very dangerous from set pieces, and the way in which he scored the excellent winning goal - well, not many players can do that."

Heynckes (l.) and Martinez (r.) helped Bayern become the first German club to win the treble in 2012/13.

Martinez boasts several qualities that make him a perfect link between the Bayern backline of Mats Hummels and Jerome Boateng, and his more attack-minded midfield partners Thiago Alcantara, Arturo Vidal and Corentin Tolisso. His reading of the game is second to none, which allows him to snuff out opposition attacks long before they approach Bayern's penalty area. He is also strong in the tackle and has fantastic aerial presence.

The Spaniard occupied the holding role throughout Bayern's remarkable 2012/13 campaign under Heynckes, and he was instrumental in delivering that historic treble of Bundesliga, DFB Cup and Champions League. Though he has gone on to win four more league titles with the club, injuries and uncertainty about his best position mean that he has never quite exerted the same influence on the Bavarians' game. Until now.

"Javi is fiercely important, a key factor in why we've been less likely to concede over the past few weeks," insisted goalkeeper Sven Ulreich, echoing his coach's words. "He gives us greater stability in defence. He makes very intelligent runs and closes down the space."

Bayern have kept clean sheets in three of the five Bundesliga games Martinez has started this season.

Indeed, Bayern have conceded just one goal in three Bundesliga outings with Martinez back in defensive midfield under Heynckes, compared to 12 in 11 matches under Ancelotti and Willy Sagnol. But as he showed against Celtic - and with a superb assist for Robert Lewandowski in the Bundesliga win over RB Leipzig - he can also make a difference at the other end of the pitch.

"Javi's incredibly important, of course," Arjen Robben added. "He played more as a centre-back last season and now he's back in defensive midfield, playing very well when we don't have the ball. He also got the winning goal against Celtic, so you can only give him credit. He's so important in that defensive midfield role, just as he was during our very successful previous spell with Jupp Heynckes."

Renewed optimism with Heynckes and renewed stability with Martinez - things are certainly looking up at Bayern Munich. Five points adrift of Borussia Dortmund a month ago, the champions have now opened up a six-point gap over their rivals at the top of the Bundesliga with victory in Der Klassiker. Martinez provided another full-blooded performance and was not on the pitch when Dortmund grabbed their single goal, and looks almost certain to remain the rock in the champions' rejuvenated defence.

Andy Smith

Click here for more Bayern Munich news, views and features!