Lazio coach Maurizio Sarri was left frustrated after their 2-2 draw with Empoi.
Lazio blew a 2-0 lead late on to drop two points on Sunday.
“We played a very good game," said Sarri.
“We deserved to score more than two goals. Then we were naive when we conceded a goal having six players inside our box and just two on the ball. The rest is just bad luck, we were still in control after conceding the first goal.
“We have this huge mental fatigue issue. If you look at the physical aspect, the stats for the first and second halves are almost identical. What is different is the level of focus and commitment.
“We struggle to keep our level all the 90 minutes. I fear it depends on our mental strength, we are showing some lack of it. It looked like we were on the right track, but then these issues came out again…
“Can we fix it? Of course, we can try to improve. However, we already put a lot of commitment and intensity during our training sessions, so it's difficult to get much further than that.
“What's our goal? First of all, we must put an end to this period, otherwise it's hard to talk about goals".