World champions France made it two wins from two matches with a 4-0 victory over Iceland.
Les Bleus, wearing a vintage kit to mark the centenary of the French Football Federation, took the lead after 12 minutes when Paris St Germain star Kylian Mbappe sent over a corner and Samuel Umtiti nodded into the bottom corner.
France had to wait until midway through the second half to double the lead, Olivier Giroud tapping home a cross from Benjamin Pavard.
The floodgates then opened with Mbappe and Antoine Griezmann wrapping up an ultimately-comprehensive win.
Elsewhere in Group H, Everton striker Cenk Tosun scored twice as Turkey thumped Moldova 4-0 and Albania won 3-0 in Andorra.
Cristiano Ronaldo went off injured as reigning European champions Portugal were held 1-1 at home to Serbia in their Euro 2020 qualifier.
The 34-year-old could now be a doubt for Juventus when they face Ajax in the Champions League quarter-finals, with the first leg on April 10.
Dusan Tadic put the visitors ahead from the penalty spot in the seventh minute after Rui Patricio fouled Mijat Gacinovic.
Things got worse for Portugal when skipper Ronaldo appeared to tweak a hamstring and had to be substituted after half an hour.
Portugal equalised before the interval thanks to Danilo Pereira's drive into the top corner from outside the box, but they could not force a winner and were unlucky not to be awarded a late penalty after the referee overturned his own handball decision.
Ukraine are the early pace-setters in Group B after a last-gasp 2-1 win in Luxembourg.
Ross Barkley scored two goals and made another as England came from behind to beat Montenegro 5-1.
Raheem Sterling, the hat-trick hero of Friday's 5-0 win over Czech Republic, also grabbed a goal and created two more in another impressive display from the Three Lions.
Montenegro took a shock 17th-minute lead when Marko Vesovic burst through and bent his shot past the outstretched hand of England keeper Jordan Pickford.
But England levelled 12 minutes later when defender Michael Keane met Barkley's inviting free-kick with a header at the far post for his first senior international goal.
Seven minutes before half-time Barkley fired England ahead when he got a touch on Callum Hudson-Odoi's curling effort.
And the Chelsea midfielder doubled England's lead just before the hour, finishing from 10 yards after being teed up by Sterling.
Sterling squared the ball for skipper Harry Kane to slot home the fourth, and the Manchester City forward slipped the fifth through the legs of goalkeeper Danijel Petkovic before pointedly celebrating in front of the Montenegro fans.
Bulgaria, one of England's main rivals in Group A, were held to a 1-1 draw in Kosovo, Arber Zeneli's equaliser giving the hosts a point from their first ever qualifying match.