Men of iron meet in Manchester

Marked parallels
Although Hierro is four years Keane's senior, there are parallels between the pair, who are the loudest voices in their respective dressing rooms. Hierro began his career as a central midfield player before retreating into the heart of defence - a positional change that midfield dynamo Keane has often been tipped to emulate. Additionally, both players have enjoyed long spells with one club - Hierro having joined Madrid from Real Valladolid in 1989 while Keane left Nottingham Forest FC for Old Trafford in 1993.

Glorious careers
With glorious careers already behind them, you might expect the desire of the 31-year-old Keane and the 35-year-old Hierro to have subsided somewhat. Indeed, former Republic of Ireland captain Keane's recent decision to finally retire from international football in order to extend his club career and guard against a recurrence of knee and hip problems had prompted many to write him off.

'I feel really strong'
However, speaking ahead of tonight's match, in which his side need to claw back a 3-1 deficit to reach the semi-finals, Keane was keen to stress that his body and mind are still willing. "A lot has been made of my injuries," he said. "Maybe a lot of that has been my own fault, maybe I've spoken too much about them, but the last two, three weeks I feel really strong physically and mentally. I feel the sharpness is definitely back."

Single-minded Hierro
Hierro displays a similar single-mindedness. "The most important thing right now is to get through to the semi-finals of the Champions League," he told uefa.com. "This is my only focus. I want to return to Old Trafford to play football once more this season [for the final]."

'Everyone here works hard' 
Another trait the players share is a refreshing unwillingness to live off their reputations. "There are no stars in the dressing room just professionals," Hierro said. "Everyone here works hard and has respect for the club. I know that some people call us the Harlem Globetrotters of football but we don't like this. We have demonstrated that we're a serious team by winning the Champions League trophy three times in five years."

'The players stood off too much' 
Keane lives by a similar philosophy, and has always been quick to identify what he sees as the weaknesses in the United side. "There was a lot we learnt from the first game [in Madrid]," he said. "In the first half if anything the players stood off too much. Hopefully that will not be the same scenario [on Wednesday]. "

Intimidating standards
The standards Keane sets are intimidating to some, but he makes no apologies. "Our European form over the past two years has been good," he said. "But the ultimate is going on to win it. Like Madrid have done nine times. That's the benchmark I set myself and my team-mates. It's no good talking the talk, you've got to walk the walk."

Voracious hunger
Hierro's hunger is similarly voracious. "To win the Champions League this season would be very special because it is our centenary year at the club and it would also be our tenth European title," he said. "We all know how important it is for the club and the fans to maintain our status as the best in Europe."

Additional reporting by Julia Court