How to update pip3 in Xubuntu 18.04?

Question

pip

I need a newer version of pip3 to install some packages. However, after the update, it is not possible to use the latest version - an error occurs.

[email protected]:~$ which pip3
/usr/bin/pip3
[email protected]:~$ pip3 -V
pip 9.0.1 from /usr/lib/python3/dist-packages (python 3.6)
[email protected]:~$ pip3 install --upgrade  pip
Collecting pip
  Using cached https://files.pythonhosted.org/packages/c2/d7/90f34cb0d83a6c5631cf71dfe64cc1054598c843a92b400e55675cc2ac37/pip-18.1-py2.py3-none-any.whl
Installing collected packages: pip
Successfully installed pip-18.1
[email protected]:~$ which pip3
/usr/bin/pip3
[email protected]:~$ pip3 -V
Traceback (most recent call last):
  File "/usr/bin/pip3", line 9, in <module>
    from pip import main
ImportError: cannot import name 'main'
[email protected]:~$ python3 -m pip --version
pip 18.1 from /home/yura/.local/lib/python3.6/site-packages/pip (python 3.6)
[email protected]:~$

What do you advise?