Alexander-Arnold settling in as Real Madrid target Club World Cup glory
The England international created the only goal of the game for Gonzalo Garcia as Xabi Alonso's side beat Italian giants Juventus 1-0 in the last 16.
With Alonso moving to a back three as soon as he had the personnel available, Alexander-Arnold has benefitted from playing as a right wing-back in their last two matches.
That is where he is set to continue against German outfit Dortmund in New Jersey on Saturday at the MetLife Stadium.
Alexander-Arnold's floated cross for Gonzalo against Juventus was the precise kind of attacking output that led Madrid to bring him in.
"He could have had many more assists already," said Los Blancos goalkeeper Thibaut Courtois.
"In training, he is horrible to play against. His corner kicks are another level.
"I don't think I have seen a guy like this with such quality. As a goalkeeper it is a nightmare, but it will help make me better."
Madrid skipper Dani Carvajal is back from a long-term injury but may end up being used more as a centre-back than in the wing-back position now that Alexander-Arnold has arrived.
Los Blancos paid as much as 10 million euros ($11.75 million) according to reports to sign the 26-year-old a month before his Liverpool deal expired, but have already made approximately 54 million euros for reaching the Club World Cup quarter-finals.
After struggling a little at right-back against Al Hilal in Madrid's opening 1-1 draw, Alexander-Arnold has steadily improved.
Manchester City's 4-3 defeat by the Saudi Arabian club showed in hindsight the defender's problems were not entirely of his own making.
Repeat with a twist
As well as beating Dortmund in the 2024 Champions League final, Madrid came from two goals behind to thrash them 5-2 this season in the group phase of the same competition. However both teams have changed significantly since then.
They have new coaches, in the newly-appointed Alonso and Dortmund's Niko Kovac, who has done a fine job since arriving in January, helping them secure qualification for next season's Champions League.
Alexander-Arnold and Dean Huijsen's arrivals have shaken up Madrid's defence, while Borussia Dortmund brought in Jobe Bellingham from Sunderland.
However the midfielder's yellow card against Monterrey in the 2-1 last 16 win means he is suspended for the clash against Madrid and will therefore not face his older brother Jude Bellingham.
Madrid's French striker Kylian Mbappe did not score in the rout of Dortmund in October amid a crisis of confidence, but since then has found top form.
After returning from a stomach bug as a substitute against Juventus, Mbappe will be keen to start against the Bundesliga side and add to his tally of 43 goals.
The former Paris Saint-Germain star, who is on a collision course with his former club in the semi-finals should they both progress, could come in for Gonzalo, despite the 21-year-old scoring three goals at the tournament.
"It's inexplicable," said the forward, whom Alonso compared to former Madrid great Raul, saying Gonzalo had some of the same qualities.
"I saw a great ball coming in from Trent, I saw Rudiger didn't get to it and I said to myself, 'this is mine!'" added Gonzalo of his goal against Juventus.
Alonso, who arrived at Madrid from Bayer Leverkusen, will take on his former Bundesliga rivals Dortmund.
"We know (him) very well, he worked two and a half years in Germany, and he did a fantastic job," said Kovac.
"Now he's implementing everything he had in Leverkusen at Real Madrid. So we're expecting the same what we had in Leverkusen, only with different players.
"We're looking forward to it but you have to play football for 90 minutes, and if we put everything onto the pitch, the same performance as we saw (against Monterrey), I think that we will have a good chance."