MILAN, Feb 21 (Reuters) - Serie A leaders Inter Milan are not used to losing and their reaction to the 2-0 Champions League defeat at Liverpool will be key for Sunday's trip to Sampdoria (1400 GMT).
Tuesday's reverse in the last 16 first leg tie at Anfield was only the second defeat of the season for Inter, who lost 1-0 at Fenerbahce in the group stages in September.
Roberto Mancini's men lead Serie A by 11 points and Italy's top bookmaker has suspended betting on them retaining the scudetto.
However, Inter could not have picked a worse time to visit seventh-placed Sampdoria, one of the league's in-form teams thanks to some stunning performances from forward Antonio Cassano, including last weekend's 1-0 win in the Genoa derby.
Inter will also be without centre back Ivan Cordoba, who might be out for the season after injuring knee ligaments against Liverpool.
Team harmony is also at risk after striker Zlatan Ibrahimovic publicly expressed his anger towards defender Marco Materazzi, who was harshly sent off at Anfield.
The defeat, in which Inter conceded two late goals, hit Swede Ibrahimovic especially hard.
'It was horrible, like a dagger to the heart after all the work we put in,' he was quoted as saying in Thursday's Gazzetta dello Sport.
In contrast, second-placed AS Roma host Fiorentina in fourth on Sunday (1400) high on confidence after a 2-1 win over Real Madrid in their Champions League clash on Tuesday.
Roma's Brazil defender Juan is doubtful with an ankle knock.
The Real win came despite team mates Christian Panucci and Alberto Aquilani coming to blows in training before the game after anger spilled over from last weekend's 1-0 defeat at third-placed Juventus.
Claudio Ranieri's Juve are just a point behind the Rome side but are likely to travel to second-bottom Reggina on Saturday (1930) without goalkeeper Gianluigi Buffon, who has a bad back.
Fifth-placed AC Milan, three points behind Fiorentina, host Palermo in Sunday's late game (1930) with keeper Zeljko Kalac poised to play having come through Wednesday's 0-0 Champions League draw at Arsenal despite dislocating a finger.