In mammals, each sperm has exactly the haploid set of chromosomes and each egg another haploid set, and during the process of fertilization a zygote with the diploid set is produced.
Each sperm has exactly the haploid set of chromosomes. This is in mammals. Each sperm has each egg another haploid set. This is in mammals. A zygote with the diploid set is produced. This was during the process of fertilization. This was in mammals.