Lampard is delighted with their deal for Ajax midfielder Ziyech and was asked if more signings could be made.
He said, "I don't know. We have to worry first about where we're at.
“Trying to come in the top four is the priority for us so my main concern is that. But we're always on the lookout and we're always working together to see how we can improve.
“Those improvement could be needed maybe in the summer and we'll try to make sure we get the right ones."