Montjeu, the defending Prix de l`Arc de Triomphe champion, is among 13 acceptors for the race on Sunday that is billed as the middle distance championship of Europe.
The French star, odds on with British bookmakers to retain his crown at Longchamp, showed up well during a light workout at Chantilly on Monday.
Principal opposition is expected to come from the top Irish and German three-year-olds, Sinndar and Samum.
Sinndar, gutsy in the Epsom Derby and majestic In the Irish version, gained vital course experience in the group two Prix Niel in which he overwhelmed the opposition.
Samum, the unbeaten German Derby winner and current third favourite, lived up to his reputation in the group one Grosser Preis von Baden.
He dismissed high class domestic and British opposition with contempt on that occasion and is clearly at the height of his powers.
Eight of Monday`s 13 acceptors are domestically-trained and include the group one Prix Vermeille winner and third-placed finisher, Volovoreta and Egyptband.
Montjeu`s pacemaker, Stop By, group two winners Russian Hope and Daring Hope, plus fellow outsiders Hesiode and Hightori are also among the octet.
Air Shakur, a Japanese classic winner, has first hand experience of the devastating power of Montjeu, having been well held to fifth in the King George VI and Queen Elizabeth Diamond Stakes at Ascot, England, in July.
