Llorente had a hand in the Swans’ goal at Turf Moor but the World Cup-winning Spain striker struggled against Hull.
The 31-year-old headed one chance over the bar and, although he attempted to link up with his team-mates, the former Juventus and Athletic Bilbao striker looked laboured as the game wore on.
“Fernando needs time to understand our ways and the Premier League. It’s normal because he has just arrived,” said Guidolin.
“If I had the possibility of playing with Borja in the last 20 minutes, I would have done. It’s normal for Fernando to be tired.”
As well as their attacking shortcomings, Swansea also showed a familiar frailty at set-pieces against Hull as they conceded Shaun Maloney’s opening goal from a corner.
Guidolin highlighted set-pieces as a weakness last season, and the Italian recognises his side still have work to do in that area.
“It’s a step back and we have to return to our work on the training field,” he added.
“We have to improve at set-pieces. I am confident in my players. Last season, we had the possibility to improve with set-pieces and it’s important we improve both offensively and defensively this season.”