Benfica, as history shows however, have almost always been the more successful out of the two Lisbon clubs, and they soon returned to being Portugal's premier club, winning six league titles out of the last ten seasons.
It's about 1 3/4 miles between the two - how about a rather swift walk! Maybe just leave the Benfica game 5 mins from the end if you see that the score wont change, and you will be one the first to leave the stadium, jump on a taxi to Alvalade stadium which is not that far, just over a mile.