Mikel Merino bettered a feat previously achieved by David Silva and Isco in Spain's 4-0 win over Bulgaria.
The Arsenal midfielder scored the opening two goals in Valladolid, before an own goal and a Mikel Oyarzabal penalty sealed another comfortable victory for Luis de la Fuente's side.
Merino's first effort in the 4-0 victory saw him become the first Spanish midfielder to score at least five goals in a World Cup qualifying campaign since Silva and Isco netted five goals apiece in qualifying for the 2018 tournament.
However, Merino bettered the former Manchester City star and the Real Betis playmaker by netting a second to take his tally to six goals in four appearances in the qualifying campaign.
Merino equals De Bruyne goals tally
As a result, the 29-year-old is the joint-highest scoring midfielder in the UEFA section of the 2026 World Cup qualifying, sharing the honour with Napoli and Belgium's Kevin De Bruyne.
However, De Bruyne has had the advantage of playing in a five-team group, while Spain are competing in a group that contains just four nations.
Merino has reached his impressive tally by scoring in the opening qualifier against Bulgaria and netting his first international hat-trick in September's 3-0 win over Turkey.
After scoring a brace in Tuesday's return fixture against Bulgaria, Merino will be keen to continue his impressive form in Spain's final two qualifiers against Georgia and Turkey in November.
The midfielder is just one goal away from equalling Memphis Depay's tally in the European World Cup qualifying scoring charts, although he is six goals adrift of top scorer Erling Haaland.
Spain equal record unbeaten run
Merino's double in Valladolid helped Spain maintain their perfect record in qualifying and extend their unbeaten run to 29 competitive matches (W24, D5).
As a result, they have equalled their longest unbeaten run in competitive games, which was previously set under Victor Del Bosque between 2010 and 2023.
Luis de la Fuente's charges will have the opportunity to set a new record when they face Georgia in Tbilisi on November 15.