A defendant’s testimony on a collateral matter may be the subject of impeachment by a rebuttal witness. The defendant testified that during the time of an attempted robbery he was driving his boss’ van, that he worked at a particular address as an auto mechanic, and that he had driven it as his work van for four months. It was not error for the court to allow the prosecution to call the disabled owner of the van to testify that he did not operate any business, he had owned the van for only two months, and he gave the defendant permission to drive it. There was no abuse of discretion to allow the rebuttal testimony over a section 352 objection. Under Evidence Code section 351 all relevant evidence is admissible and section 780 provides that the credibility of a witness may be considered based on the existence or nonexistence of any fact testified to by him. Contrary to the Attorney General’s argument, there is no rule that testimony “opened the door” to impeachment; this is “a ‘popular fallacy’ and rejected by courts and commentators alike.” The trial court simply has discretion to permit relevant evidence or exclude collateral evidence under section 352. Here, the contradicting testimony was relevant as bearing on the defendant’s credibility.