You can play the excerpt in tune. You have played it in tune a hundred times. Then you walk into the audition room, the panel nods, and the same F sharp you have owned for a month lands flat enough that you hear it, they hear it, and the next two lines are spent recovering instead of playing.
Here is the part nobody tells you: your ear did not get worse. Your hands changed. Intonation under pressure is a physical problem wearing a musical costume, and you can train for it the same way you train a shift.
What actually moves when you are nervous
Adrenaline does specific, predictable things to a string player. Your bow arm carries more weight than you gave it. Your vibrato gets wider and faster, which drags the center of the pitch with it. Your left hand grips, so fingers land heavy and slightly high, then correct late. Shifts overshoot because the motion that was calibrated at practice-room arousal is now running on a different nervous system.
None of that is a knowledge problem. You know where the note is. The calibration you built in the practice room was built on calm hands, and calm hands are not what you brought into the room.
This is why the advice to just practice more misses. More repetitions at calm calibration make the calm version stronger. They do not teach the nervous version anything.
Hear the drift before you fix it
Most intonation under pressure fails in one direction per player. Some players pull sharp when they grip. Most drift flat on descending lines as the hand tires and the middle finger lands short. You have a signature. Find it.
Record a take when the stakes feel real: first run of the morning, no warmup, phone propped on the stand, one take only. Then listen back against a drone on the tonic. The notes that pull will pull the same way almost every time.
When the Judge scores a take, intonation is measured as center-of-pitch on every note plus drift across the take, in cents. That is the same thing your panel's ears are doing, just written down. However you measure it, the point is the same: get the drift on paper, because a named problem is a trainable problem.
Train the collapse, not just the notes
Once you know your signature, build pressure into the practice loop on purpose. One-take recordings, cold starts, a real or imagined audience. The goal is to spend time playing while slightly uncomfortable, because slightly uncomfortable is the room.
Drone work is the backbone. Set a long tonic drone, play the passage slowly against it, and listen for which notes beat against the drone. Then speed it up in stages without losing the beat-free landing. The drone gives your ear a reference that does not flinch when you do.
Last, rehearse the recovery. A note lands wide in the room and the next three notes decide your score, because the panel forgives one smudge and remembers a spiral. Practice landing a bad note on purpose and continuing with a quiet hand. That skill alone is worth points.