DES Bulpin had to settle for a point on his debut as Weymouth's new director of football.
But the high-flying visitors should have claimed all three as they twice took the lead with strikes from Ian Hutchinson and David Laws during a frantic eleven minute spell midway through the second period only to be quickly pegged back on each occasion.
But it seemed like all their good work would go down the drain when substitute Jason Rowbotham was sent-off for recklessly clashing with City's Jon Challinor late on.
That meant the Terras spent most of the closing stages battling to keep out the hosts and it took a stubborn rearguard display to earn them a valuable draw. In a drab and unimaginative opening period chances were at a premium.
But when championship-chasing Weymouth did fashion a couple of decent openings, they were guilty of failing to take full advantage.
It was striker Lee Phillips who was the main culprit - screwing his close range shot wide early on and then blazing a volley over the top after City keeper Matt Nurse's weak punch fell invitingly to him on the penalty spot.
For their part, the hosts - who also underwent managerial upheaval last week with Chris Tovey walking out to be replaced by caretaker boss Andy Kirkup - never really caused Terras' number one Danny Potter to sweat, although the former Exeter man had to have his wits about him to turn Martin Fox's speculative left-footed shot onto the bar.
But Weymouth should have gone ahead seconds before the interval when Mark Robinson nodded Michael Dean's dangerous corner back across goal and into the path of Alex Browne who was just three yards out.
However the club captain somehow failed to hit the target with the goal gaping in front of him. Things really livened up after the break with both sides looking far more likely.
Rob Nightingale's volley was a whisker away from giving the hosts the lead but it was Weymouth who hit the front following a sweeping counter attack on 61 minutes.
The devastating move ended with substitute Darran Rowbotham, who had only been thrown on a minute earlier, sending Hutchinson away with his first touch and the hard-working midfielder kept his cool to beat Nurse with a cracking low drive.
But that advantage lasted just six minutes as the Whites got back on terms when Franco Nacca's quickly taken free-kick found Kevin Wilkin who nipped in at the far post to prod home.
Potter then came to the visitors rescue, denying Nightingale with a reflex save from point-blank range.
With the full-blooded contest now well and truly an end-to-end affair, it came as no surprise when Weymouth took the lead for a second time on 70 minutes.
Another swift break resulted in Phillips doing well to work some space on the right before cutting inside and picking out the predatory Laws at the far post who had the simple task of tucking home.
But Cambridge refused to give in and they hauled themselves level again just 90 seconds later.
A deep cross from left-back Fox was met by big defender Steve Holden who got in front of Potter to steer his header into the back of the net. And the Terras received another setback almost immediately when Jason Rowbotham was sent off after appearing to have lashed out at the theatrical Challinor, who was booked for diving.
The closing stages were a case of hanging on to a point for Weymouth who were grateful on more than one occasion to some stout defending in and around a packed box. However it was that man Laws who almost had the final say but his instinctive long-range lob agonisingly flew inches
wide
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