Montoya won a brave battle of wills with title front-runner Alonso at the British Grand Prix at Silverstone 11 days ago as he duelled with the Spaniard in the first few corners before the Renault driver eventually gave way.
Such an incident appeared to indicate Montoya is back in form after the early part of his season was wrecked by a shoulder injury.
It means Alonso now not only has one McLaren to contend with in championship rival Kimi Raikkonen, but with Montoya back on the scene, that potentially spells double trouble for the 23-year-old in his quest to become Formula One’s youngest champion.
“Juan Pablo is always very aggressive in a race situation and is not a good guy to have a fight with because you can finish in the grass quite easily,” said Alonso, who currently leads Raikkonen by 26 points going into this weekend’s German Grand Prix.
“Because the McLaren is quick, and they will always be competitive, then it is not a help for me, which means he could be a help for Kimi.
“I’m sure there will be times when Juan Pablo, team-mate Giancarlo Fisichella and also Michael Schumacher will help me in some races and take points off Kimi, but there will also be times when they take points off me.”
Alonso’s fears are underlined by the fact he rates Raikkonen and McLaren as the “best package” in Formula One.
But for engine failures in the last two grands prix, resulting in a 10-place demotion down the grid, the gap would be a lot closer between the two protagonists as Raikkonen has stormed his way to a podium finish on each occasion.
At least there is a healthy respect between Alonso and Raikkonen as he added: “I’ve know Kimi since 1997 from go-karts and we have always had a good relationship, no problems.
“There’s not much conversation, like all Formula One drivers, but there’s a lot of respect for each other.
“He is a great driver and I am very proud to fight with him because he is the best on the grid, in that he has the best package at the moment.
“After three years at McLaren he knows the team perfectly, knows the car, and together they’ve been very strong all season.
“So to fight with him is very hard for me, but much better than with some other names, although it doesn’t worry me much. It’s nothing new.
“Since Imola they have had the best package, but we’ve won near enough the same number of races since then,” he said.
In the meantime, Nicolas Kiesa has been handed the role of Friday test driver with Jordan ahead of the German Grand Prix.
Kiesa replaces Robert Doornbos, who earlier this week was named as a Minardi driver for the remainder of the season after the team opted to release Patrick Friesacher due to his sponsorship money drying up.
“I am very excited about the opportunity,” he said.