In the winter of 1474–75, probably between december and January, Leonardo assisted Verrocchio with the design of a standard for a magnificent joust sponsored by Giuliano de’ Medici, Lorenzo's tall and athletic younger brother (fig. 16). Ostensibly, the event celebrated a defensive treaty negotiated between Florence, Venice, and Milan – reconfirming their nonaggression pact of 1454–55. However, such jousts (mock duels on horseback), not to be confused with tournaments (mock wars on horseback), took place annually in Florence, as a regular part of carnival and as a rite of passage for aristocratic and prominent young men, whose participation signaled that they had reached the qualifying age for public office. Held on 29 January 1475, Giuliano's joust, meant to rival one alla franciosa organized by Lorenzo in 1469, had all the pageantry and chivalric splendor of a medieval French romance – part of a long, anachronistic tradition of “knight errantry” in Florence. Having designed a standard for Lorenzo's contest, Verrocchio knew exactly what was required for Giulio's.

Now preserved in the Uffizi, the standard drawing was apparently begun by Verrocchio, who established the positions of the figures in black chalk, and finished by Leonardo, who reinforced the master's lines with pen and ink and then added plants at left, shading them with his distinctive left-handed, backward-slanting, hatching. Fitted into the long, triangular format of a standard, the two figures represent the winged, love god Cupid (or Amor), and a young woman, either a terrestrial Venus or a maiden nymph, in an untenable, recumbent posture; when Leonardo took over the execution of the drawing, he seems to have misinterpreted the placement of the large rock, which likely was intended to support her (proper) right arm. Verrocchio appears to have reused the pose he had invented for a terracotta Sleeping Youth (now in Berlin).