Voeller has to act as peacemaker between the two men, who rarely speak to each other.
Voeller is under pressure to take sanctions against Lehmann, who has said publicly that he should be number one and has made controversial comments about Kahn's lifestyle, and the coach plans a trip to London soon to speak to the Arsenal man.
"I felt for some time that something was wrong but I didn't expect it would come out that way," said Voeller.
"I'll do what I think is right. I will not let emotions blind me. I will talk to Jens about the situation calmly but clearly."
Lehmann brought the problem into the spotlight in an interview with German soccer magazine Kicker last week, saying he had been more consistent than Kahn this season.
Since joining Arsenal from Borussia Dortmund last July, the 34-year-old Lehmann has indeed been outstanding while Bayern Munich's Kahn, also 34, has made one or two uncharacteristic blunders.
"I think the way he (Lehmann) is playing makes you think he is right," Arsenal manager Arsene Wenger said after the unbeaten premier league leaders took a firm grip in the title race with a 2-1 win at Chelsea on Saturday.
"Overall I think anybody who sees every game of Arsenal would say that for us he has just been outstanding."
"I respect Oliver Kahn but I also respect somebody who wants to be the best and Lehmann wants to be the best. After that it's down to Voeller to give him a chance or not."
FIRST CHOICE
Kahn, named FIFA's player of the tournament in the 2002 World Cup, is Germany's captain and has been first choice for nearly six years, winning 66 caps.
Lehmann has 16 caps after years as a frustrated back-up.
Lehmann, who makes no secret of his difficult relationship with Kahn, made things even worse when his criticism went beyond the players' relative goalkeeping abilities.
"I didn't know we were supposed to talk," Lehmann told Kicker when asked why the two did not speak to each other.
"I don't have a 24-year-old girlfriend. I have a different life."
Lehmann
"I am deeply hurt by Lehmann's statements," said Kahn, who plans to carry on until the 2006 World Cup finals on home soil. "This is as low as it can get."
Lehmann has since apologised, saying he should not have brought up Kahn's private life, but the damage was done.
"Lehmann's statements are uncooperative and in bad taste," said Franz Beckenbauer, Germany's most respected soccer personality and the president of Bayern.
"Rudi Voeller has to consider this carefully and act accordingly," added the World Cup-winning captain and coach.
FAMILIAR INCIDENT
The incident sounded all too familiar to Beckenbauer, who was the Germany coach when he had to face a similar situation at the 1986 World Cup finals in Mexico.
Harald (Toni) Schumacher was then Germany's number one and reserve Uli Stein, out of frustration, verbally attacked Beckenbauer, who kicked him out of the team and sent him home.
Kahn was Germany's number two goalkeeper for years and had to wait until Andreas Koepke retired after the 1998 World Cup in France to become the number one.
The frustration for Lehmann is that he will almost certainly be regarded as too old to take over by the time Kahn ends his international career.
With the Euro 2004 finals in June, Voeller needs to make a move swiftly.
Lehmann has said he could imagine travelling to Portugal as the number two but it remains to be seen whether he will be allowed to.
By criticising Kahn, Lehmann attacked not only a rival goalkeeper but also a symbol of what has made Germany such an intimidating force for decades.
A great motivator and a true leader, Kahn has always been driven by success and was instrumental in his side's unexpected recovery from a lean spell with their run to the 2002 World Cup final.
Germany have failed to shine since and Voeller would have probably preferred to spend his energy on other areas of the team.
However, for the moment he has no choice.
(Additional reporting by Bill Barclay)
