(Reuters) - Argentina face Germany in the Davis Cup first round this weekend on shakier ground at home than when they beat their opponents 4-1 away at the same stage last year.

World number seven Juan Martin del Potro is not playing the Davis Cup at all this year having decided he wants to concentrate fully on trying to break into the world's top four.

Tennis players from Germany (L) and Argentina pose for a picture after the official draw of their upcoming Davis Cup tennis match in Buenos Aires January 31, 2013. Germany and Argentina will play their first round match in Buenos Aires over the coming weekend. (L - R) The German tennis players include Christopher Kas, Florian Mayer, Tobias Kamke, Philipp Kohlschreiber and team captain Carsten Arriens; while the Argentine players include team captain Martin Jaite, Carlos Berlocq, Juan Monaco, Horacio Zeballos and David Nalbandian. REUTERS/Marcos Brindicci

This has gone down badly with many of his compatriots, who criticise his lack of commitment to a national cause to bring the famous salad bowl trophy home for the first time after losing four finals, three since 2006.

However, Argentina beat Germany last year without 2009 US Open champion Del Potro who only came into the team at the quarter-final stage.

"Being at home is very important, we must not lose sight of that," captain Martin Jaite said as a rallying cry to his team in the build-up to the tie.

What Argentina lack on their favoured clay court at Parque Roca is a fully fit Juan Monaco and David Nalbandian.

Monaco, ranked 12 and drawn on Thursday to meet Florian Mayer in the second singles, has been troubled by a wrist problem and also picked up a thigh muscle tear at the Australian Open.

Nalbandian helped Argentina win last year's tie 3-0 on the second day after winning his opening singles match and then the doubles with Eduardo Schwank.

The veteran campaigner, however, has been out of action for six months through injury and is only playing the doubles with Horacio Zeballos in the absence of Schwank, who is recovering from wrist surgery.

Carlos Berlocq will open the tie against world number 19 Phillip Kohlschreiber having made his Davis Cup debut in last year's semi-final at home to the Czech Republic.

Berlocq stood in for the injured Del Potro in the decisive last singles and lost to Tomas Berdych.

In head-to-head meetings, Monaco is 5-1 down to Mayer and Berlocq 3-1 down to Kohlschreiber.

(Writing by Rex Gowar in London; editing by Toby Davis)

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