MADRID (AFP) - Champions League holders Barcelona host Russian champions Rubin Kazan at Camp Nou on Tuesday aiming to tighten their grip at the top of Champions League Group F.

Barcelona top the group by a point above Dynamo Kiev, with Inter Milan two points back in third, and are strong favourites to dispose of Rubin in a David versus Goliath contest.

French striker Thierry Henry, one of six Barcelona players nominated for the Ballon D?Or award, is out injured with a thigh injury while Zlatan Ibrahimovic is also a doubt with a knee knock sustained on international duty with Sweden.

Both forwards were absent for Barcelona?s 0-0 league draw with Valencia on Saturday that ended their 100 percent start to the season although the treble winners still lead the Spanish table.

"We went to Valencia trying to win but they made it very difficult for us," admitted Barcelona coach Pep Guardiola. "We are not capable of winning all 38 league games."

A boost for Guardiola and Barcelona has been the return to fitness and form of Andres Iniesta who missed pre-season through injury.

"I am improving little by little and I am feeling much better," said Spanish international Iniesta.

With Kiev and Inter facing off in Milan it is a good chance for Barcelona to turn the screw in the group although Rubin showed they can compete with the top teams in their last group match when they drew 1-1 with 10-man Inter and could have taken all the points.