Visiting Eintracht Frankfurt stunned West Ham United 2-1, while its Bundesliga colleague RB Leipzig fought to a 1-0 home win over Scottish giant Rangers in their respective Europa League matches on Thursday.
Daichi Kamada nudged the winner for Frankfurt early in the second half to the delight of the 3,000 fans who backed the Eagles in London.
And Frankfurt will be dreaming of a trip to Seville for the May 18 final if it can survive next week's home leg but will be aware it can take nothing for granted against West Ham.
The host side canceled Ansgar Knauff's first-minute opener through Michail Antonio before the break and also hit the woodwork three times – the last a thumping overhead kick off the bar from Jarrod Bowen in injury-time.
Leipzig in contrast dominated throughout against Rangers but struggled to create chances against the defensive Scottish champions.
Christopher Nkunku somehow failed to add to his 30 season goals when he rounded keeper Allan McGregor only to blaze off-target but Angelino's superb 85th minute volley finally made the breakthrough.
"We can thank Angelino for this super shot," teammate Benjamin Henrichs said, while the scorer said "we have deserved" the victory.
An all Bundesliga final could be possible in the competition for the first time since 1980 when Frankfurt defeated Borussia Monchengladbach on away goals.
The second leg to come in Glasgow, however, remains finely balanced with that away goals no longer in force from this season.
Frankfurt fell in its last Europa League semifinal in London, losing to Chelsea in 2019, but Knauff's back-post header in just 49 seconds gave them the lead.
Antonio bundled in a free-kick to level and West Ham had a period of control before Frankfurt regained the initiative.
A lovely move saw Djibril Sow's shot saved only for Kamada to walk onto the rebound and an empty net.
"Today wasn't one of our best performances," Antonio told BT Sport. "It's two legs. We'll go there and put in the work and you never know.
"It's all to play for. We're in it to win it.
"Another game to go. No matter where we go we believe we can beat anybody."
Said Benrahma curled a wonderful long-shot onto the post and Bowen beat keeper Kevin Trapp at the death only for his magnificent overhead kick to rattle the woodwork but Frankfurt survived for another famous victory after it eliminated Barcelone last time.
In between Kamada had his own shot deflected onto the post as Eintracht looked to kill the tie.
"We have a very good starting position," Trapp told RTL. "There were a lot of positive emotions."
Leipzig enjoyed 75% possession in the first half against Rangers but managed just four shots and McGregor did not have a save to make.
That changed after the break but Rangers looked to have held on until a corner fell for Angelino five minutes from time and the full back volleyed sweetly into the corner from the edge of the box.
And Leipzig, who is also in the German Cup final, will feel confident at moving closer to the potential maiden title in its history as Rangers will have to attack more at home.
"We just wanted to stay compact and make it hard from them to get through us," Rangers midfielder Joe Aribo said.
"It's all about concentration and hard work, that's what we did out there."