A first-half Dominic Solanke penalty sent Tottenham to a 1-0 win at Eintracht Frankfurt on Thursday and into the semi-finals of the Europa League 2-1 on aggregate.

Under fire amid a terrible Premier League campaign and with coach Ange Postecoglou's job hanging by a thread, Spurs put in the type of controlled performance they have lacked this campaign.

After Frankfurt's Hugo Ekitike and Spurs' Mathys Tel traded first-half chances, home goalkeeper Kaua Santos' nasty collision in the box with James Maddison brought Solanke to the spot.

Without a goal since January, Solanke made no mistake, giving Spurs the lead in front of Frankfurt's raucous Nordwestkurve.

The win will prove a stay of execution for Postecoglou, keeping alive Spurs' chance of reaching the final in Bilbao along with the coach's oft-maligned guarantee of winning a title in his second season at a club.

The loss ends Frankfurt's hopes of returning to Spain to again lift the Europa League title, having done so three years ago in Seville.

Despite the defeat, Frankfurt sit third in the league and are on track for their best league finish since the mid-1990s.

Postecoglou travelled to Germany knowing only victory would give him hope of staying in the job beyond the season.

With the club on track for their worst league finish in three decades, the Europa League was the final remaining chance for the Australian to make good on his promise of "always" winning trophies in his second season.

Spurs' suffered a fresh setback came the day before the match, with Son Heung-min ruled out of the trip with a foot injury.

With kickoff just minutes away, Frankfurt fans unfurled a 80-metre tall banner of their Eagle mascot cradling the club's trophies, including the 2022 Europa League, a reminder to the visitors of their recent success.

Just as in the first leg, Frankfurt's attack was focused on the elegant Hugo Ekitike.

The French striker had a golden chance to put the hosts in front after 16 minutes when through on goal, but the lightning-quick van de Ven got a timely touch on the ball before Ekitike could get a shot away.

Frankfurt were on top but lost midfield veteran Mario Goetze to a hamstring injury soon after and the home side struggled to adjust without their attacking fulcrum.

Mathys Tel, back in Germany for the first time since moving to Spurs from Bayern Munich on loan in winter, forced a fingertip save from a flying Santos with 25 minutes gone.

Santos' willingness to put his body on the line may have him soon set to take over from club stalwart and captain Kevin Trapp, but his eagerness cost Frankfurt shortly before halftime.

Cristian Romero spun in a looping cross for Maddison but the midfielder was taken out mid-air by Santos before crumpling to the turf, with a penalty awarded on VAR review.

Solanke's first task was taking the ball from the eager Tel, but after Postecoglou signalled from the bench, the England striker stepped up and converted, scoring his first goal since January.

Santos was shown a yellow but the tackle rattled Maddison, who was subbed off shortly after.

With time running down in the second half, Spurs dropped back allowing Frankfurt possession in dangerous spaces but the hosts were unable to level things up.