Liverpool didn't need to get out of second gear against Porto at Anfield, with a 0-0 enough to see the Reds into the Champions League quarter-finals for the first time since the 2008/09 campaign with a 5-0 aggregate win.
In what was a subdued first half at Anfield, Sadio Mane looked the brightest player in a Liverpool shirt and had the two best chances of the period.
The Senegal international then went even closer on the half hour.
Liverpool started the second half with much more purpose, as a sliced Milner effort from just inside the 18-yard box with little over two minutes played suggesting Jurgen Klopp wanted more from his side in the second period.
The visitors meanwhile had the first shot that was on target in the game, as Abdul Waris' low strike from distance was pushed to safety by an untroubled Loris Karius, as the tempo of the game soon reached a lull once more.
Roberto Firmino then saw his effort blocked well by Porto captain Felipe on the hour, before making way for Danny Ings.
Half chances soon followed for either side, although they failed to truly trouble both Karius and Casillas in their respected goals.
Sergio Conceicao's side had a great chance in the final 10 minutes to leave Anfield with a consolation goal, but Oliver Torres saw his strike blocked well by Dejan Lovren to keep their clean sheet in tact.
Casillas then rolled back the years with a stunning save at full stretch to deny Ings a first Champions League goal late on to keep the scoreline goalless.
It didn't matter however as the Reds' 5-0 triumph at the Estadio do Drago three weeks ago ended the tie as a contest, as referee Felix Zwayer signalling for full-time, and confirming Liverpool's passage into the quarter-finals of the Champions League for the first time in nine years.