Portugal had an early effort controversially disallowed by the video referees but they eventually took the lead after 34 minutes through Ricardo Quaresma after a mistake by Carlos Salcedo let Cristiano Ronaldo through on goal.
Vega first failed to connect with a cross from winger Hirving Lozano early in the game and then sent a header narrowly wide in the 26th minute.
Robin van Persie returns to the Dutch attack to face Mexico in the second round of the World Cup on Sunday while Mexican defender Hector Moreno will lock horns with his former mentor Louis van Gaal.
Mexico's national team has launched a campaign to discourage fans from shouting homophobic slurs during football matches.
Mexico, needing only a draw to reach the World Cup round of 16, were level 0-0 with Sweden at half-time in their Group F match on Wednesday, after surviving an aerial bombardment and a VAR review.
Manchester United's Luke Shaw is set to undergo a second operation on Friday after breaking his right leg in two places in Tuesday's 2-1 loss to PSV Eindhoven, according to British media reports.
Manchester United defender Luke Shaw is expected to be sidelined for at least six months after breaking his right leg in two places, manager Louis van Gaal said on Friday.
Mexico striker Javier Hernandez had surgery on a fractured collarbone and will be out for four weeks missing the Gold Cup, the Mexican Football Federation (FMF) said.
PSV Eindhoven will miss striker Luuk de Jong when they entertain Atletico Madrid in the first leg of the Champions League last 16 on Wednesday.
Juan Mata hailed George Best "a genius forever" as an injury-hit Manchester United aim to mark the 10th anniversary of the Northern Irishman's death with a Champions League victory against PSV Eindhoven on Wednesday.
Mexico got just rewards for their attacking intent when Oribe Peralta's 61st minute strike gave them a 1-0 win over Cameroon in their World Cup opener at a rain-saturated Dunas arena on Friday.
Germany were stunned 1-0 by Mexico in the opening game of their World Cup defence on Sunday as Hirving Lozano finished off a sharp counter-attack that exposed the ragged defending that the four-times winners had displayed in their warm-up games.
Neymar scored the opener to continue his rich vein of form as 10-man Barcelona won a one-sided La Liga derby against Espanyol.
Neymar shrugged off some rough tackling and a missed penalty to score a brilliant solo goal as he led Brazil to a 3-0 win over Paraguay that moved them within sight of the 2018 World Cup finals on Tuesday.
Photos from the Champions League matches played across Europe on Tuesday
Lionel Messi, Luis Suarez and Neymar combined to devastating effect as Barcelona swatted Celtic aside 7-0 at the Nou Camp to lay down a marker in Champions League Group C on Tuesday.