In State Hwy Comm v. Redmon, 42 Mich. App. 642; 202 N.W.2d 527 (1972), the Court emphasized the defendant's dilatory conduct in affirming the trial court's decision denying the defendant's motion to strike the plaintiff's known expert witness. In Redmon, a condemnation case, the expert witness the plaintiff named in the pretrial summary suffered a heart attack that rendered him unable to testify. Id. at 644. The plaintiff notified the defendant five months before trial of the expert's incapacitation, and fifty-six days before trial that substitution was required because of the witness' continuing disability. Id. After the jury was sworn, defendant moved for the first time to exclude the plaintiff's substituted expert on grounds that the expert was not listed on the plaintiff's pretrial statement and that she had been informed of the plaintiff's intent to use the expert only after the period for such disclosure had expired. Id. In affirming the trial court's decision denying the defendant's motion to strike, this Court focused on the defendant's dilatory conduct and held: The trial court carefully pointed out that at no time did counsel for defendant voice any objection to the court or opposing counsel on the subject of the substitution before trial. It is difficult to believe defendant raised objection at trial in good faith. by failing to raise timely objection to the proposed new expert witness, defendant gave the plaintiff every reason to believe that the substitution had been accepted and waived her right to object at trial. While the court's pretrial summary usually controls the subsequent course of litigation, the trial court is allowed discretionary power under GCR 1963, 301.3 to modify the pretrial summary at or before trial so as to avoid manifest injustice. We have consistently upheld this discretion of the trial court in the exclusion and admission of witnesses and evidence not listed at pretrial in the absence of clear abuse. Defendant's counsel did not challenge the technicality of substituting witnesses after the time for disclosure had passed in a timely fashion, but rather sat back to raise the issue at trial. to paraphrase Justice Butzel in People v. Elliott, 322 Mich. 313, 316 33 N.W.2d 811 (1948), counsel cannot sit idly by and then for the first time interpose objections at trial. T he plaintiff informed defendant "of the expert's name as soon as it was determined he would be a witness and in sufficient time so that plaintiff defendant in this case could have prepared to meet his testimony, no matter what it might have been." The facts justified denial of defendant's motion. We therefore affirm the trial court's ruling. Redmon, 42 Mich. App. at 645-646.