Although it may save time, dodging the pre-workout warmup is a surefire way to get injured during a tough workout. Have a dedicated warmup that involves bodyweight exercises like lunges, squats, pushups, and jumping jacks to elevate your heart rate before you attack the weights head on. No matter how short of a time you have, always include a quick warmup in your workout.
Furthermore, before a big compound lift—like a squat or a deadlift—start with a warmup set with more reps at a lighter weight. It'll further increase blood flow to your muscles, and help you cue up good form before you start going heavy. If you simply don’t have a ton of time to get in your lifting session, shorten rest periods and cut out a set of each exercise rather than ditching the warmup.