Eager to make an impression on his debut, midfielder Maikel Kieftenbeld left a late tackle on Nathaniel Chalobah to register his first booking in Millwall colours.

The Hornets came closer still after 35 minutes when Tom Cleverley sent a teasing cross into the box which Shaun Hutchinson inadvertently turned onto a post before eventually coming back into the danger area and falling to Gray, who fired high and wide.

The prospect of half-time then brought a flurry of chances as Deeney slipped in Ismaila Sarr, who was forced into a tight angle before firing straight at goalkeeper Bartosz Bialkowski.

At the other end, Jake Cooper lost his marker and turned a Danny McNamara cross onto a post and away from goal. And moments later Cooper did have the ball in the back of the net but was adjudged to have been offside.

Clear-cut chances proved just as hard to come by in the second half as both defences stood up to the tests of the attackers.

With just under half-an-hour to go, Scott Malone crafted a chance for himself with an outside-of-the-boot shot but his effort was wide of the target.

Białkowski remained untested for a further 10 minutes until Chalobah unleashed a fierce long-range effort which was parried into a dangerous area for Deeney to attempt a spectacular overhead-kick and force a double save from the Lions stopper.

Sarr was next to test his luck after the ball fell kindly to him following a corner but the Senegal international was unable to control the ball well enough to get decent contact on the strike.

Millwall boss Gary Rowett used all of his available substitutes to try and push for all three points but neither side was able to steal the points at the end.

The Hornets are now six points behind leaders Norwich, who have a game in hand, while Rowett and the Lions are 15th.