Spain maintained their place at the top of Group G with an 8-0 thrashing of Liechtenstein, capping a week of impressive performances in World Cup qualifying for Julen Lopetegui's side.
Braces from Alvaro Morata and Iago Aspas as well as further strikes from Sergio Ramos, Isco, David Silva and an own goal gave the 2010 world champions a comfortable stroll to victory in Vaduz on a night the hosts offered little resistance.
Dominant Spain took a 4-0 lead into half-time, which marked the first time they'd scored four or more goals in the first half of a competitive match since the 2013 Confederations Cup in Brazil, when they hammered Tahiti 10-0 in a group-stage game at the Maracana.
The win gives them 22 points from eight matches and a three-point advantage over second-placed Italy, who they beat 3-0 at the Santiago Bernabeu on Saturday. They need four points from their remaining two games to be completely certain of a place in the finals -- though their goal difference advantage over Italy means one win will do it.
However, Italy bounced back from that defeat with a 1-0 home victory over fourth-placed Israel in their group match in Reggio Emilia.
Ciro Immobile's 53rd-minute goal made the difference, giving Giampiero Ventura's reeling side some consolation and solidifying their standing over third-placed Albania, who, in the group's other game drew against Macedonia 1-1.
It means Italy now appear all but guaranteed of second place in the group and a place in the playoffs, sitting six points ahead of Albania with two games left to play and with a vastly superior goal difference.
Serbia moved to within one win of qualifying for the finals with a crucial 1-0 Group D win away to Republic of Ireland -- Martin O'Neill's first defeat in Dublin in his four years in charge.
Roma defender Aleksandar Kolarov scored the only goal of the game 10 minutes after the break, but the Irish were given hope in the 68th minute when Nikola Maksimovic was sent off for tripping Daryl Murphy when the striker was about to go through on goal.
The Republic pushed and pushed for an equaliser, with Cyrus Christie blazing over the bar, but Serbia stood firm.
Wales needed late goals again to keep their dreams of a first World Cup since 1958 alive, Hal Robson-Kanu heading home in the 80th after good work from Ben Woodburn and Aaron Ramsey netting in stoppage time for a 2-0 win in Moldova.
The victory means Wales are a point ahead of Ireland in what looks to be a two-horse race for second place, with Wales still to go to Georgia and Ireland hosting Moldova before the two nations mean each other in Cardiff on the final matchday.
Austria are still just mathematically in with a chance of second place but a draw a 1-1 home to Georgia caused them more damage. Valeriane Gvilia put the visitors in front in the eighth minute before Louis Schaub levelled two minutes before the interval.
In the congested Group I, Gylfi Sigurdsson scored twice to help Iceland move level on points at the top with a 2-0 win over Ukraine.
In a controverisial opener just after half-time, Sigurdsson was on hand to tap home after Iceland striker Johann Gudmundsson collided with Ukraine keeper Andriy Pyatov.
The Everton midfielder added a second after a counter-attack in the 66th minute, taking the ball off the foot of teammate Jon Dadi Bodvarsson to lash home.
Iceland recovered from a stunning defeat in Finland last week and are now on 16 points, just second on goal difference behind leaders Croatia, who suffered a 1-0 defeat away to Turkey.
With the game still level in the 75th minute, Oguzhan Ozyakup fired a hard shot from distance that Croatia keeper Danijel Subasic could only parry back into the box, and Cenk Tosun stepped up to volley home the winner.
With two games remaining, Turkey and Ukraine are third and fourth, both on 14 points with a plus-4 goal difference.
Finland beat Kosovo 1-0 with Teemu Pukki's 83rd-minute goal, though both teams were already eliminated entering the day.