Spain suffered a shock World Cup qualifying defeat in Sweden while Euro 2020 winners Italy were held by Bulgaria.
Spain's defeat in Solna was their first World Cup qualifying loss since 1993 and leaves them second in Group B behind the Swedes, who have played a game fewer but won all three of their matches thus far.
Debutant Carlos Soler volleyed the visitors into an early lead but Alexander Isak levelled almost immediately before Viktor Claesson ended Spain's 66-game unbeaten run in the qualifiers with a second-half winner.
Italy, meanwhile, extended their undefeated sequence to 35 games but had to settle for a point in Florence as Stanas Iliev's equaliser for Bulgaria cancelled out Federico Chiesa's opener for Roberto Mancini's side.
The Azzurri remain top of Group C with 10 points from four games, while Northern Ireland got off the mark in the same group with a 4-1 win in Lithuania.
Shayne Lavery and Daniel Ballard scored their first international goals while Conor Washington and Paddy McNair both netted from the spot - although the visitors were grateful for a Bailey Peacock-Farrell penalty save with the score at 2-1.
It gave Ian Baraclough a first competitive win inside 90 minutes a year after his first game in charge and – given it was achieved without the likes of Jonny Evans, Stuart Dallas and Josh Magennis – offers a big confidence boost ahead of Wednesday’s qualifier against Switzerland at Windsor Park.
Elsewhere, Timo Werner and Leroy Sane scored as Germany limped to a 2-0 win in Liechtenstein, while Romelu Lukaku bagged a brace as Belgium recovered from conceding a second-minute goal to win 5-2 in Estonia.