The treble-chasing Champions League finalists, who have already bagged the Italian Cup, have a two-point lead at the top over AS Roma and are also in great form as they travel to a side long relegated.
Constant media reports about Mourinho possibly leaving for Real Madrid at the end of the season could have knocked a lesser team off their stride but the likes of captain Javier Zanetti can control their match-day emotions like ultra-reliable robots.
Mourinho has tried his best to stem the speculation, issuing a statement saying he has not spoken with any clubs and is concentrating solely on Siena and the May 22 Champions League final, but he also keeps leaving the door open.
"I'm in love with my players and the fans, not Italian football," he told Reuters this week.
His outspoken character has led him into trouble several times during his two seasons at Inter and he is currently being probed by the soccer federation after joking that Roma would pay Siena to beat his team.
Unlike angry Roma, who visit mid-table Chievo Verona on Sunday hoping for a shock scudetto, Siena president Massimo Mezzaroma has laughed off Mourinho's comments.
"It's a way of taking pressure off his own team. He's doing it in a respectable way," he told reporters.
SECURE IN THIRD
Whether Siena's proud players see it that way remains to be seen and Mourinho runs the risk that they will be extra-motivated for their final Serie A game.
With relegation and two Europa League places already sorted out, the other issue to be decided on Sunday is the fourth Champions League qualifying spot.
Fourth-placed Sampdoria host Napoli on Sunday and have a two-point lead over Palermo, who visit relegated Atalanta.
AC Milan welcome Juventus on Saturday in a rare example of a game between the two famous sides meaning so little.
Milan are secure in third and Juve will finish a disappointing seventh but there could be one development from the game should home coach Leonardo announce he is leaving.
Meanwhile Juve's search for a new coach to replace interim boss Alberto Zaccheroni looks far from over.
Milan and Juve are such a sideshow this term that the game has been moved to the Saturday instead of Sunday so it does not clash with Inter's potential title party in the city.
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