Well I've decided to go with the overs bet on this game. Let's start by looking at both teams record in the competiton:
Overall Records
Inter Milan 4 4 0 0 10 : 2 12
Cagliari 6 4 0 2 14 : 9 12
Cagliari's Route to the Semi-Final
Sampdoria v Cagliari 3:2
Cagliari v Sampdoria 2:0
Lazio v Cagliari 3:2aet
Cagliari v Lazio 2:1
Cagliari v Triestina 3:1
Triestina v Cagliari 1:3
Inter's Route to the Semi-Final
Inter Milan v Atalanta 3:0
Atalanta v Inter Milan 0:1
Bologna v Inter Milan 1:3
Inter Milan v Bologna 3:1
Inter have only conceded 2 goals in the competion so far, a statistic which I expect to change tonight against strong home side Cagliari. Looking at the Serie A performance of Inter we can see that their 30 away goals makes them the highest scoring team on the road.
Cagliari are impressive at home having only lost once in Serie A all season. However, they have also drawn 8 of those 18 home games. In the 3 home cup games they've only kept a clean sheet once against Sampdoria. Cagliari know that they really have to win tonight as it will be very difficult for them to get a result in the San Siro in the return leg. Therefore I believe they will come out to attack Inter and try to get the required victory. This should leave gaps for Inter to exploit.
I really couldn't pick a winner here, if it was the league I would favour Cagliari, but the nature of cup competition is different. I predict an open match which should hopefully have a few goals.
4 units on over 2.5 goals @ 1.98 Betfair