Bayern Munich made the most of several slices of good fortune to beat Sevilla and put themselves on course for the Champions League semi-finals.
The German giants fell behind to a Pablo Sarabia strike - the Sevilla forward having earlier missed a gilt-edged opening - but they battled back to earn a 2-1 win thanks to two massively-deflected goals.
The first saw Franck Ribery's 38th-minute cross go in off Jesus Navas and then Thiago's second-half header found the back of the net via Sergio Escudero.
Bayern, who stepped up through the gears after being second best for the opening 45 minutes, will now fancy their chances of finishing things off in the return meeting at the Allianz Arena, where they have won 21 of their last 22 home Champions League matches.
The two teams came into the match on the back of contrasting fortunes at the weekend.
Sevilla led 2-0 against all-conquering Barcelona - unbeaten in LaLiga for a year - with just two minutes remaining but had to settle for a draw, while Bayern steamrollered arch-rivals Borussia Dortmund 6-0 to take a huge step towards another Bundesliga title.
Sarabia missed the Barca clash through suspension, but he returned to the Sevilla starting line-up and was at the centre of the two main talking points of the opening half-hour.
The first saw him somehow contrive to miss what looked a certain goal in the 20th minute, side-footing wide from 12 yards out with only Sven Ulreich to beat.
The 25-year-old made amends for that miss 12 minutes later, however, when he lashed Sevilla ahead.
The left-footed forward, who moments before had brought a diving parry out of Ulreich with a long-range effort, got ahead of Juan Bernat at the far post to control Escudero's cross before firing home.
Bernat appealed for handball by the Sevilla man, but the goal stood.
Bayern's problems appeared to increase soon after when they lost midfield dynamo Arturo Vidal to injury, but within two minutes of his departure Bayern were level - with replacement James Rodriguez involved.
A lightning-quick counter down the right saw the ball passed between Jerome Boateng, Thomas Muller and Rodriguez before arriving at the feet of Ribery on the left of the area.
The Frenchman's cross was meant to pick out Robert Lewandowski in the middle, but it took a big deflection off Navas and, despite the best efforts of Sevilla goalkeeper David Soria, the ball went in off the near post.
That was tough on the home side, who once again impressed on the big stage after knocking Manchester United out in the previous round.
And they picked up where they left off after the break with Franco Vazquez being denied by a fantastic goal-saving challenge by Javi Martinez.
But Bayern gradually began to awaken from their slumber and, after steadily building up pressure, they almost took the lead in the 66th minute when Martinez was denied by a wonderful save by Soria.
Sevilla were not so fortunate from Bayern's next attack.
Ribery's floated cross picked out the unmarked Thiago at the far post and his downward header went in via another decisive deflection, this time off Escudero.
Bayern sensed blood and Rodriguez brought a fine diving save out of Soria.
Sevilla made a late charge and Steven N'Zonzi fired just wide before substitute Sandro drew a fine stop out of Ulreich, but Bayern held on for a potentially decisive - if somewhat fortuitous - win.