The Buddies striker bagged both goals as Danny Lennon's side beat Motherwell on Friday night to give them a timely boost ahead of their trip north.
Caley have been in fine form this season and are second in the standings and Thompson is expects a tough game.
He said: "You would have thought the ideal tie would have been Inverness v Ross County.
"It is not great for the fans travelling and it is not great for us travelling.
"But that is the way it goes and we just need to go up there and focus.
"Inverness have scored a lot of goals and, so far, they are my team of the year.
"They are always well organised under Terry (Butcher) and Maurice (Malpas) but this season they are a force going forward.
"There is a nice shape about the team just now.
"It will be a difficult game but we need to build on the Motherwell result and string a few wins together."
While Caley Thistle have stormed up the league table, it has been a disappointing few weeks Saints, apart from Friday.
The Paisley side are eighth in the standings after a frustrating start to the campaign.
But while Buddies boss Lennon may look to strengthen his squad in the January transfer market, Thompson reckons the ideal Christmas present has arrived.
He said: "I don't know what is happening about getting new players.
"But it is good to have Paul McGowan back. That is almost like a new signing because he is a big player for us."