You are correct - that away goal by Inter might come back to haunt Lazio [ask us at Juve about the "away goals" rule in the Cup this year ....]. But I doubt it.
Interestingly, Sunday's Inter-Juve game may have some bearing on the Cup. If Juve beats Inter, Inter could simply collapse, just like Juve did at the end of last year. Particularly when it comes only days after losing Ronaldo. If that happens, Inter would be in no position to even seriously challenge you in the return leg of the Cup.
On the other hand, if Inter beats Juve on Sunday, that could get them back on track, fighting for both a Champions League spot and the Cup. Then the return leg of the Cup final might be closer.
So Lazio might be interested in the Inter-Juve game for more reasons than just the race for the scudetto.
i expect inter to be on top of its game...if not, then inter has alot to do to fix what has been a horrible year. the reason why i think they should be great against juve is because of the good news that his operation went well and he will play football again.
well, i hope they play their best game of the year against juve to help lazio catch them.
inter 2-0 juventus
lazio 3-2 fiorentina