У двери стоит чемодан.

to stand

Breakdown of У двери стоит чемодан.

• дверь: the door
• чемодан: the suitcase
• у: on

Questions & Answers about У двери стоит чемодан.

Why is it у двери and not у дверь? What does у do to the noun?

The preposition у (“at / by / near”) always requires the genitive case in Russian.

• The noun дверь (“door”) in the nominative (dictionary form) changes to двери in the genitive singular.
• So:
  
  • nominative: дверь – “(the/a) door”
  • genitive singular: двери – “of the door / by the door”

Because у takes the genitive, you must say у двери, never у дверь.

How do I know двери here is genitive singular and not nominative plural?

The form двери can be both:

• genitive singular: “of the door / by the door”
• nominative plural: “doors”

In this sentence, context and verb form tell you which it is.

• The verb стоит is singular, so it’s describing one subject (here: чемодан).
• Чемодан (singular) is clearly the subject.
• That means у двери must be “by the door” (genitive singular), not “by the doors”.

If it were plural “doors” with a plural subject, you’d get something like:

• У дверей стоят чемоданы. – “There are suitcases by the doors.”
  (Here дверей is genitive plural, чемоданы and стоят are plural.)